ETH Price: $2,418.71 (-1.26%)

Transaction Decoder

Block:
15697533 at Oct-07-2022 04:54:23 PM +UTC
Transaction Fee:
0.00223863385399875 ETH $5.41
Gas Used:
119,250 Gas / 18.772610935 Gwei

Emitted Events:

83 WifeBoredApe.TransferSingle( operator=[Receiver] ZeroEx, from=0x7a53dbbcf0d4470800aef89a3c6c1f2c9c3102bc, to=[Sender] 0x0311663d459db2314b6f8f2859e535ff6da56eed, id=29, value=1 )
84 ZeroEx.0x20cca81b0e269b265b3229d6b537da91ef475ca0ef55caed7dd30731700ba98d( 0x20cca81b0e269b265b3229d6b537da91ef475ca0ef55caed7dd30731700ba98d, 0000000000000000000000000000000000000000000000000000000000000000, 0000000000000000000000007a53dbbcf0d4470800aef89a3c6c1f2c9c3102bc, 0000000000000000000000000311663d459db2314b6f8f2859e535ff6da56eed, 000000000000000000000000000000000000000000000000000001838fbb7739, 000000000000000000000000eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee, 0000000000000000000000000000000000000000000000000022d10c4ecc8000, 000000000000000000000000e0eac59cb4c5576d9deda4e08b03c081851d4a46, 000000000000000000000000000000000000000000000000000000000000001d, 0000000000000000000000000000000000000000000000000000000000000001, 0000000000000000000000000000000000000000000000000000000000000000 )

Account State Difference:

  Address   Before After State Difference Code
0x0311663d...f6Da56Eed
0.015315230793981685 Eth
Nonce: 181
0.003276596939982935 Eth
Nonce: 182
0.01203863385399875
0x7a53Dbbc...c9C3102bc 0.118933364266686615 Eth0.128733364266686615 Eth0.0098
(Flashbots: Builder)
1.180768682487706843 Eth1.181007182487706843 Eth0.0002385
0xDef1C0de...027b25EfF
(0x: Exchange Proxy)
0xe0EaC59c...1851D4a46

Execution Trace

ETH 0.0098 ZeroEx.7cdb54d8( )
  • ETH 0.0098 ERC1155OrdersFeature.buyERC1155( sellOrder=[{name:direction, type:uint8, order:1, indexed:false, value:0, valueString:0}, {name:maker, type:address, order:2, indexed:false, value:0x7a53DbbcF0d4470800aeF89A3C6c1F2c9C3102bc, valueString:0x7a53DbbcF0d4470800aeF89A3C6c1F2c9C3102bc}, {name:taker, type:address, order:3, indexed:false, value:0x0000000000000000000000000000000000000000, valueString:0x0000000000000000000000000000000000000000}, {name:expiry, type:uint256, order:4, indexed:false, value:1665168562, valueString:1665168562}, {name:nonce, type:uint256, order:5, indexed:false, value:1664563771193, valueString:1664563771193}, {name:erc20Token, type:address, order:6, indexed:false, value:0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE, valueString:0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE}, {name:erc20TokenAmount, type:uint256, order:7, indexed:false, value:9800000000000000, valueString:9800000000000000}, {name:fees, type:tuple[], order:8, indexed:false}, {name:erc1155Token, type:address, order:9, indexed:false, value:0xe0EaC59cB4C5576d9DEDa4E08b03c081851D4a46, valueString:0xe0EaC59cB4C5576d9DEDa4E08b03c081851D4a46}, {name:erc1155TokenId, type:uint256, order:10, indexed:false, value:29, valueString:29}, {name:erc1155TokenProperties, type:tuple[], order:11, indexed:false}, {name:erc1155TokenAmount, type:uint128, order:12, indexed:false, value:1, valueString:1}], signature=[{name:signatureType, type:uint8, order:1, indexed:false, value:2, valueString:2}, {name:v, type:uint8, order:2, indexed:false, value:27, valueString:27}, {name:r, type:bytes32, order:3, indexed:false, value:640B9EF45F94778F1BA28A3194318CBF10A7740CC460AC7A1F5EDC0349D093BB, valueString:640B9EF45F94778F1BA28A3194318CBF10A7740CC460AC7A1F5EDC0349D093BB}, {name:s, type:bytes32, order:4, indexed:false, value:62BBC5ED1CD52C2945C207E2BE392C10E0C3A7BBF650FD9E2094EAE6CA4394FE, valueString:62BBC5ED1CD52C2945C207E2BE392C10E0C3A7BBF650FD9E2094EAE6CA4394FE}], erc1155BuyAmount=1, callbackData=0x )
    • Null: 0x000...001.fb7d75f9( )
    • WifeBoredApe.safeTransferFrom( from=0x7a53DbbcF0d4470800aeF89A3C6c1F2c9C3102bc, to=0x0311663d459db2314B6F8f2859E535ff6Da56Eed, id=29, amount=1, data=0x )
    • ETH 0.0098 0x7a53dbbcf0d4470800aef89a3c6c1f2c9c3102bc.CALL( )
      File 1 of 3: ZeroEx
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
      import "./migrations/LibBootstrap.sol";
      import "./features/Bootstrap.sol";
      import "./storage/LibProxyStorage.sol";
      import "./errors/LibProxyRichErrors.sol";
      /// @dev An extensible proxy contract that serves as a universal entry point for
      ///      interacting with the 0x protocol.
      contract ZeroEx {
          // solhint-disable separate-by-one-line-in-contract,indent,var-name-mixedcase
          using LibBytesV06 for bytes;
          /// @dev Construct this contract and register the `Bootstrap` feature.
          ///      After constructing this contract, `bootstrap()` should be called
          ///      to seed the initial feature set.
          constructor() public {
              // Temporarily create and register the bootstrap feature.
              // It will deregister itself after `bootstrap()` has been called.
              Bootstrap bootstrap = new Bootstrap(msg.sender);
              LibProxyStorage.getStorage().impls[bootstrap.bootstrap.selector] =
                  address(bootstrap);
          }
          // solhint-disable state-visibility
          /// @dev Forwards calls to the appropriate implementation contract.
          fallback() external payable {
              bytes4 selector = msg.data.readBytes4(0);
              address impl = getFunctionImplementation(selector);
              if (impl == address(0)) {
                  _revertWithData(LibProxyRichErrors.NotImplementedError(selector));
              }
              (bool success, bytes memory resultData) = impl.delegatecall(msg.data);
              if (!success) {
                  _revertWithData(resultData);
              }
              _returnWithData(resultData);
          }
          /// @dev Fallback for just receiving ether.
          receive() external payable {}
          // solhint-enable state-visibility
          /// @dev Get the implementation contract of a registered function.
          /// @param selector The function selector.
          /// @return impl The implementation contract address.
          function getFunctionImplementation(bytes4 selector)
              public
              view
              returns (address impl)
          {
              return LibProxyStorage.getStorage().impls[selector];
          }
          /// @dev Revert with arbitrary bytes.
          /// @param data Revert data.
          function _revertWithData(bytes memory data) private pure {
              assembly { revert(add(data, 32), mload(data)) }
          }
          /// @dev Return with arbitrary bytes.
          /// @param data Return data.
          function _returnWithData(bytes memory data) private pure {
              assembly { return(add(data, 32), mload(data)) }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      import "./errors/LibBytesRichErrorsV06.sol";
      import "./errors/LibRichErrorsV06.sol";
      library LibBytesV06 {
          using LibBytesV06 for bytes;
          /// @dev Gets the memory address for a byte array.
          /// @param input Byte array to lookup.
          /// @return memoryAddress Memory address of byte array. This
          ///         points to the header of the byte array which contains
          ///         the length.
          function rawAddress(bytes memory input)
              internal
              pure
              returns (uint256 memoryAddress)
          {
              assembly {
                  memoryAddress := input
              }
              return memoryAddress;
          }
          /// @dev Gets the memory address for the contents of a byte array.
          /// @param input Byte array to lookup.
          /// @return memoryAddress Memory address of the contents of the byte array.
          function contentAddress(bytes memory input)
              internal
              pure
              returns (uint256 memoryAddress)
          {
              assembly {
                  memoryAddress := add(input, 32)
              }
              return memoryAddress;
          }
          /// @dev Copies `length` bytes from memory location `source` to `dest`.
          /// @param dest memory address to copy bytes to.
          /// @param source memory address to copy bytes from.
          /// @param length number of bytes to copy.
          function memCopy(
              uint256 dest,
              uint256 source,
              uint256 length
          )
              internal
              pure
          {
              if (length < 32) {
                  // Handle a partial word by reading destination and masking
                  // off the bits we are interested in.
                  // This correctly handles overlap, zero lengths and source == dest
                  assembly {
                      let mask := sub(exp(256, sub(32, length)), 1)
                      let s := and(mload(source), not(mask))
                      let d := and(mload(dest), mask)
                      mstore(dest, or(s, d))
                  }
              } else {
                  // Skip the O(length) loop when source == dest.
                  if (source == dest) {
                      return;
                  }
                  // For large copies we copy whole words at a time. The final
                  // word is aligned to the end of the range (instead of after the
                  // previous) to handle partial words. So a copy will look like this:
                  //
                  //  ####
                  //      ####
                  //          ####
                  //            ####
                  //
                  // We handle overlap in the source and destination range by
                  // changing the copying direction. This prevents us from
                  // overwriting parts of source that we still need to copy.
                  //
                  // This correctly handles source == dest
                  //
                  if (source > dest) {
                      assembly {
                          // We subtract 32 from `sEnd` and `dEnd` because it
                          // is easier to compare with in the loop, and these
                          // are also the addresses we need for copying the
                          // last bytes.
                          length := sub(length, 32)
                          let sEnd := add(source, length)
                          let dEnd := add(dest, length)
                          // Remember the last 32 bytes of source
                          // This needs to be done here and not after the loop
                          // because we may have overwritten the last bytes in
                          // source already due to overlap.
                          let last := mload(sEnd)
                          // Copy whole words front to back
                          // Note: the first check is always true,
                          // this could have been a do-while loop.
                          // solhint-disable-next-line no-empty-blocks
                          for {} lt(source, sEnd) {} {
                              mstore(dest, mload(source))
                              source := add(source, 32)
                              dest := add(dest, 32)
                          }
                          // Write the last 32 bytes
                          mstore(dEnd, last)
                      }
                  } else {
                      assembly {
                          // We subtract 32 from `sEnd` and `dEnd` because those
                          // are the starting points when copying a word at the end.
                          length := sub(length, 32)
                          let sEnd := add(source, length)
                          let dEnd := add(dest, length)
                          // Remember the first 32 bytes of source
                          // This needs to be done here and not after the loop
                          // because we may have overwritten the first bytes in
                          // source already due to overlap.
                          let first := mload(source)
                          // Copy whole words back to front
                          // We use a signed comparisson here to allow dEnd to become
                          // negative (happens when source and dest < 32). Valid
                          // addresses in local memory will never be larger than
                          // 2**255, so they can be safely re-interpreted as signed.
                          // Note: the first check is always true,
                          // this could have been a do-while loop.
                          // solhint-disable-next-line no-empty-blocks
                          for {} slt(dest, dEnd) {} {
                              mstore(dEnd, mload(sEnd))
                              sEnd := sub(sEnd, 32)
                              dEnd := sub(dEnd, 32)
                          }
                          // Write the first 32 bytes
                          mstore(dest, first)
                      }
                  }
              }
          }
          /// @dev Returns a slices from a byte array.
          /// @param b The byte array to take a slice from.
          /// @param from The starting index for the slice (inclusive).
          /// @param to The final index for the slice (exclusive).
          /// @return result The slice containing bytes at indices [from, to)
          function slice(
              bytes memory b,
              uint256 from,
              uint256 to
          )
              internal
              pure
              returns (bytes memory result)
          {
              // Ensure that the from and to positions are valid positions for a slice within
              // the byte array that is being used.
              if (from > to) {
                  LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                      LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                      from,
                      to
                  ));
              }
              if (to > b.length) {
                  LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                      LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                      to,
                      b.length
                  ));
              }
              // Create a new bytes structure and copy contents
              result = new bytes(to - from);
              memCopy(
                  result.contentAddress(),
                  b.contentAddress() + from,
                  result.length
              );
              return result;
          }
          /// @dev Returns a slice from a byte array without preserving the input.
          ///      When `from == 0`, the original array will match the slice.
          ///      In other cases its state will be corrupted.
          /// @param b The byte array to take a slice from. Will be destroyed in the process.
          /// @param from The starting index for the slice (inclusive).
          /// @param to The final index for the slice (exclusive).
          /// @return result The slice containing bytes at indices [from, to)
          function sliceDestructive(
              bytes memory b,
              uint256 from,
              uint256 to
          )
              internal
              pure
              returns (bytes memory result)
          {
              // Ensure that the from and to positions are valid positions for a slice within
              // the byte array that is being used.
              if (from > to) {
                  LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                      LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                      from,
                      to
                  ));
              }
              if (to > b.length) {
                  LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                      LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                      to,
                      b.length
                  ));
              }
              // Create a new bytes structure around [from, to) in-place.
              assembly {
                  result := add(b, from)
                  mstore(result, sub(to, from))
              }
              return result;
          }
          /// @dev Pops the last byte off of a byte array by modifying its length.
          /// @param b Byte array that will be modified.
          /// @return result The byte that was popped off.
          function popLastByte(bytes memory b)
              internal
              pure
              returns (bytes1 result)
          {
              if (b.length == 0) {
                  LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                      LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanZeroRequired,
                      b.length,
                      0
                  ));
              }
              // Store last byte.
              result = b[b.length - 1];
              assembly {
                  // Decrement length of byte array.
                  let newLen := sub(mload(b), 1)
                  mstore(b, newLen)
              }
              return result;
          }
          /// @dev Tests equality of two byte arrays.
          /// @param lhs First byte array to compare.
          /// @param rhs Second byte array to compare.
          /// @return equal True if arrays are the same. False otherwise.
          function equals(
              bytes memory lhs,
              bytes memory rhs
          )
              internal
              pure
              returns (bool equal)
          {
              // Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
              // We early exit on unequal lengths, but keccak would also correctly
              // handle this.
              return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
          }
          /// @dev Reads an address from a position in a byte array.
          /// @param b Byte array containing an address.
          /// @param index Index in byte array of address.
          /// @return result address from byte array.
          function readAddress(
              bytes memory b,
              uint256 index
          )
              internal
              pure
              returns (address result)
          {
              if (b.length < index + 20) {
                  LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                      LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                      b.length,
                      index + 20 // 20 is length of address
                  ));
              }
              // Add offset to index:
              // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
              // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
              index += 20;
              // Read address from array memory
              assembly {
                  // 1. Add index to address of bytes array
                  // 2. Load 32-byte word from memory
                  // 3. Apply 20-byte mask to obtain address
                  result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
              }
              return result;
          }
          /// @dev Writes an address into a specific position in a byte array.
          /// @param b Byte array to insert address into.
          /// @param index Index in byte array of address.
          /// @param input Address to put into byte array.
          function writeAddress(
              bytes memory b,
              uint256 index,
              address input
          )
              internal
              pure
          {
              if (b.length < index + 20) {
                  LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                      LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                      b.length,
                      index + 20 // 20 is length of address
                  ));
              }
              // Add offset to index:
              // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
              // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
              index += 20;
              // Store address into array memory
              assembly {
                  // The address occupies 20 bytes and mstore stores 32 bytes.
                  // First fetch the 32-byte word where we'll be storing the address, then
                  // apply a mask so we have only the bytes in the word that the address will not occupy.
                  // Then combine these bytes with the address and store the 32 bytes back to memory with mstore.
                  // 1. Add index to address of bytes array
                  // 2. Load 32-byte word from memory
                  // 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
                  let neighbors := and(
                      mload(add(b, index)),
                      0xffffffffffffffffffffffff0000000000000000000000000000000000000000
                  )
                  // Make sure input address is clean.
                  // (Solidity does not guarantee this)
                  input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)
                  // Store the neighbors and address into memory
                  mstore(add(b, index), xor(input, neighbors))
              }
          }
          /// @dev Reads a bytes32 value from a position in a byte array.
          /// @param b Byte array containing a bytes32 value.
          /// @param index Index in byte array of bytes32 value.
          /// @return result bytes32 value from byte array.
          function readBytes32(
              bytes memory b,
              uint256 index
          )
              internal
              pure
              returns (bytes32 result)
          {
              if (b.length < index + 32) {
                  LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                      LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                      b.length,
                      index + 32
                  ));
              }
              // Arrays are prefixed by a 256 bit length parameter
              index += 32;
              // Read the bytes32 from array memory
              assembly {
                  result := mload(add(b, index))
              }
              return result;
          }
          /// @dev Writes a bytes32 into a specific position in a byte array.
          /// @param b Byte array to insert <input> into.
          /// @param index Index in byte array of <input>.
          /// @param input bytes32 to put into byte array.
          function writeBytes32(
              bytes memory b,
              uint256 index,
              bytes32 input
          )
              internal
              pure
          {
              if (b.length < index + 32) {
                  LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                      LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                      b.length,
                      index + 32
                  ));
              }
              // Arrays are prefixed by a 256 bit length parameter
              index += 32;
              // Read the bytes32 from array memory
              assembly {
                  mstore(add(b, index), input)
              }
          }
          /// @dev Reads a uint256 value from a position in a byte array.
          /// @param b Byte array containing a uint256 value.
          /// @param index Index in byte array of uint256 value.
          /// @return result uint256 value from byte array.
          function readUint256(
              bytes memory b,
              uint256 index
          )
              internal
              pure
              returns (uint256 result)
          {
              result = uint256(readBytes32(b, index));
              return result;
          }
          /// @dev Writes a uint256 into a specific position in a byte array.
          /// @param b Byte array to insert <input> into.
          /// @param index Index in byte array of <input>.
          /// @param input uint256 to put into byte array.
          function writeUint256(
              bytes memory b,
              uint256 index,
              uint256 input
          )
              internal
              pure
          {
              writeBytes32(b, index, bytes32(input));
          }
          /// @dev Reads an unpadded bytes4 value from a position in a byte array.
          /// @param b Byte array containing a bytes4 value.
          /// @param index Index in byte array of bytes4 value.
          /// @return result bytes4 value from byte array.
          function readBytes4(
              bytes memory b,
              uint256 index
          )
              internal
              pure
              returns (bytes4 result)
          {
              if (b.length < index + 4) {
                  LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                      LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsFourRequired,
                      b.length,
                      index + 4
                  ));
              }
              // Arrays are prefixed by a 32 byte length field
              index += 32;
              // Read the bytes4 from array memory
              assembly {
                  result := mload(add(b, index))
                  // Solidity does not require us to clean the trailing bytes.
                  // We do it anyway
                  result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
              }
              return result;
          }
          /// @dev Writes a new length to a byte array.
          ///      Decreasing length will lead to removing the corresponding lower order bytes from the byte array.
          ///      Increasing length may lead to appending adjacent in-memory bytes to the end of the byte array.
          /// @param b Bytes array to write new length to.
          /// @param length New length of byte array.
          function writeLength(bytes memory b, uint256 length)
              internal
              pure
          {
              assembly {
                  mstore(b, length)
              }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibBytesRichErrorsV06 {
          enum InvalidByteOperationErrorCodes {
              FromLessThanOrEqualsToRequired,
              ToLessThanOrEqualsLengthRequired,
              LengthGreaterThanZeroRequired,
              LengthGreaterThanOrEqualsFourRequired,
              LengthGreaterThanOrEqualsTwentyRequired,
              LengthGreaterThanOrEqualsThirtyTwoRequired,
              LengthGreaterThanOrEqualsNestedBytesLengthRequired,
              DestinationLengthGreaterThanOrEqualSourceLengthRequired
          }
          // bytes4(keccak256("InvalidByteOperationError(uint8,uint256,uint256)"))
          bytes4 internal constant INVALID_BYTE_OPERATION_ERROR_SELECTOR =
              0x28006595;
          // solhint-disable func-name-mixedcase
          function InvalidByteOperationError(
              InvalidByteOperationErrorCodes errorCode,
              uint256 offset,
              uint256 required
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  INVALID_BYTE_OPERATION_ERROR_SELECTOR,
                  errorCode,
                  offset,
                  required
              );
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibRichErrorsV06 {
          // bytes4(keccak256("Error(string)"))
          bytes4 internal constant STANDARD_ERROR_SELECTOR = 0x08c379a0;
          // solhint-disable func-name-mixedcase
          /// @dev ABI encode a standard, string revert error payload.
          ///      This is the same payload that would be included by a `revert(string)`
          ///      solidity statement. It has the function signature `Error(string)`.
          /// @param message The error string.
          /// @return The ABI encoded error.
          function StandardError(string memory message)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  STANDARD_ERROR_SELECTOR,
                  bytes(message)
              );
          }
          // solhint-enable func-name-mixedcase
          /// @dev Reverts an encoded rich revert reason `errorData`.
          /// @param errorData ABI encoded error data.
          function rrevert(bytes memory errorData)
              internal
              pure
          {
              assembly {
                  revert(add(errorData, 0x20), mload(errorData))
              }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "../errors/LibProxyRichErrors.sol";
      library LibBootstrap {
          /// @dev Magic bytes returned by the bootstrapper to indicate success.
          ///      This is `keccack('BOOTSTRAP_SUCCESS')`.
          bytes4 internal constant BOOTSTRAP_SUCCESS = 0xd150751b;
          using LibRichErrorsV06 for bytes;
          /// @dev Perform a delegatecall and ensure it returns the magic bytes.
          /// @param target The call target.
          /// @param data The call data.
          function delegatecallBootstrapFunction(
              address target,
              bytes memory data
          )
              internal
          {
              (bool success, bytes memory resultData) = target.delegatecall(data);
              if (!success ||
                  resultData.length != 32 ||
                  abi.decode(resultData, (bytes4)) != BOOTSTRAP_SUCCESS)
              {
                  LibProxyRichErrors.BootstrapCallFailedError(target, resultData).rrevert();
              }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibProxyRichErrors {
          // solhint-disable func-name-mixedcase
          function NotImplementedError(bytes4 selector)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("NotImplementedError(bytes4)")),
                  selector
              );
          }
          function InvalidBootstrapCallerError(address actual, address expected)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("InvalidBootstrapCallerError(address,address)")),
                  actual,
                  expected
              );
          }
          function InvalidDieCallerError(address actual, address expected)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("InvalidDieCallerError(address,address)")),
                  actual,
                  expected
              );
          }
          function BootstrapCallFailedError(address target, bytes memory resultData)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("BootstrapCallFailedError(address,bytes)")),
                  target,
                  resultData
              );
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "../migrations/LibBootstrap.sol";
      import "../storage/LibProxyStorage.sol";
      import "./IBootstrap.sol";
      /// @dev Detachable `bootstrap()` feature.
      contract Bootstrap is
          IBootstrap
      {
          // solhint-disable state-visibility,indent
          /// @dev The ZeroEx contract.
          ///      This has to be immutable to persist across delegatecalls.
          address immutable private _deployer;
          /// @dev The implementation address of this contract.
          ///      This has to be immutable to persist across delegatecalls.
          address immutable private _implementation;
          /// @dev The deployer.
          ///      This has to be immutable to persist across delegatecalls.
          address immutable private _bootstrapCaller;
          // solhint-enable state-visibility,indent
          using LibRichErrorsV06 for bytes;
          /// @dev Construct this contract and set the bootstrap migration contract.
          ///      After constructing this contract, `bootstrap()` should be called
          ///      to seed the initial feature set.
          /// @param bootstrapCaller The allowed caller of `bootstrap()`.
          constructor(address bootstrapCaller) public {
              _deployer = msg.sender;
              _implementation = address(this);
              _bootstrapCaller = bootstrapCaller;
          }
          /// @dev Bootstrap the initial feature set of this contract by delegatecalling
          ///      into `target`. Before exiting the `bootstrap()` function will
          ///      deregister itself from the proxy to prevent being called again.
          /// @param target The bootstrapper contract address.
          /// @param callData The call data to execute on `target`.
          function bootstrap(address target, bytes calldata callData) external override {
              // Only the bootstrap caller can call this function.
              if (msg.sender != _bootstrapCaller) {
                  LibProxyRichErrors.InvalidBootstrapCallerError(
                      msg.sender,
                      _bootstrapCaller
                  ).rrevert();
              }
              // Deregister.
              LibProxyStorage.getStorage().impls[this.bootstrap.selector] = address(0);
              // Self-destruct.
              Bootstrap(_implementation).die();
              // Call the bootstrapper.
              LibBootstrap.delegatecallBootstrapFunction(target, callData);
          }
          /// @dev Self-destructs this contract.
          ///      Can only be called by the deployer.
          function die() external {
              if (msg.sender != _deployer) {
                  LibProxyRichErrors.InvalidDieCallerError(msg.sender, _deployer).rrevert();
              }
              selfdestruct(msg.sender);
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "./LibStorage.sol";
      /// @dev Storage helpers for the proxy contract.
      library LibProxyStorage {
          /// @dev Storage bucket for proxy contract.
          struct Storage {
              // Mapping of function selector -> function implementation
              mapping(bytes4 => address) impls;
              // The owner of the proxy contract.
              address owner;
          }
          /// @dev Get the storage bucket for this contract.
          function getStorage() internal pure returns (Storage storage stor) {
              uint256 storageSlot = LibStorage.getStorageSlot(
                  LibStorage.StorageId.Proxy
              );
              // Dip into assembly to change the slot pointed to by the local
              // variable `stor`.
              // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
              assembly { stor_slot := storageSlot }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      /// @dev Common storage helpers
      library LibStorage {
          /// @dev What to bit-shift a storage ID by to get its slot.
          ///      This gives us a maximum of 2**128 inline fields in each bucket.
          uint256 private constant STORAGE_SLOT_EXP = 128;
          /// @dev Storage IDs for feature storage buckets.
          ///      WARNING: APPEND-ONLY.
          enum StorageId {
              Proxy,
              SimpleFunctionRegistry,
              Ownable,
              TokenSpender,
              TransformERC20
          }
          /// @dev Get the storage slot given a storage ID. We assign unique, well-spaced
          ///     slots to storage bucket variables to ensure they do not overlap.
          ///     See: https://solidity.readthedocs.io/en/v0.6.6/assembly.html#access-to-external-variables-functions-and-libraries
          /// @param storageId An entry in `StorageId`
          /// @return slot The storage slot.
          function getStorageSlot(StorageId storageId)
              internal
              pure
              returns (uint256 slot)
          {
              // This should never overflow with a reasonable `STORAGE_SLOT_EXP`
              // because Solidity will do a range check on `storageId` during the cast.
              return (uint256(storageId) + 1) << STORAGE_SLOT_EXP;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      /// @dev Detachable `bootstrap()` feature.
      interface IBootstrap {
          /// @dev Bootstrap the initial feature set of this contract by delegatecalling
          ///      into `target`. Before exiting the `bootstrap()` function will
          ///      deregister itself from the proxy to prevent being called again.
          /// @param target The bootstrapper contract address.
          /// @param callData The call data to execute on `target`.
          function bootstrap(address target, bytes calldata callData) external;
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibCommonRichErrors {
          // solhint-disable func-name-mixedcase
          function OnlyCallableBySelfError(address sender)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("OnlyCallableBySelfError(address)")),
                  sender
              );
          }
          function IllegalReentrancyError()
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("IllegalReentrancyError()"))
              );
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibOwnableRichErrors {
          // solhint-disable func-name-mixedcase
          function OnlyOwnerError(
              address sender,
              address owner
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("OnlyOwnerError(address,address)")),
                  sender,
                  owner
              );
          }
          function TransferOwnerToZeroError()
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("TransferOwnerToZeroError()"))
              );
          }
          function MigrateCallFailedError(address target, bytes memory resultData)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("MigrateCallFailedError(address,bytes)")),
                  target,
                  resultData
              );
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibSimpleFunctionRegistryRichErrors {
          // solhint-disable func-name-mixedcase
          function NotInRollbackHistoryError(bytes4 selector, address targetImpl)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("NotInRollbackHistoryError(bytes4,address)")),
                  selector,
                  targetImpl
              );
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibSpenderRichErrors {
          // solhint-disable func-name-mixedcase
          function SpenderERC20TransferFromFailedError(
              address token,
              address owner,
              address to,
              uint256 amount,
              bytes memory errorData
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("SpenderERC20TransferFromFailedError(address,address,address,uint256,bytes)")),
                  token,
                  owner,
                  to,
                  amount,
                  errorData
              );
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibTransformERC20RichErrors {
          // solhint-disable func-name-mixedcase,separate-by-one-line-in-contract
          function InsufficientEthAttachedError(
              uint256 ethAttached,
              uint256 ethNeeded
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("InsufficientEthAttachedError(uint256,uint256)")),
                  ethAttached,
                  ethNeeded
              );
          }
          function IncompleteTransformERC20Error(
              address outputToken,
              uint256 outputTokenAmount,
              uint256 minOutputTokenAmount
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("IncompleteTransformERC20Error(address,uint256,uint256)")),
                  outputToken,
                  outputTokenAmount,
                  minOutputTokenAmount
              );
          }
          function NegativeTransformERC20OutputError(
              address outputToken,
              uint256 outputTokenLostAmount
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("NegativeTransformERC20OutputError(address,uint256)")),
                  outputToken,
                  outputTokenLostAmount
              );
          }
          function TransformerFailedError(
              address transformer,
              bytes memory transformerData,
              bytes memory resultData
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("TransformerFailedError(address,bytes,bytes)")),
                  transformer,
                  transformerData,
                  resultData
              );
          }
          // Common Transformer errors ///////////////////////////////////////////////
          function OnlyCallableByDeployerError(
              address caller,
              address deployer
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("OnlyCallableByDeployerError(address,address)")),
                  caller,
                  deployer
              );
          }
          function InvalidExecutionContextError(
              address actualContext,
              address expectedContext
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("InvalidExecutionContextError(address,address)")),
                  actualContext,
                  expectedContext
              );
          }
          enum InvalidTransformDataErrorCode {
              INVALID_TOKENS,
              INVALID_ARRAY_LENGTH
          }
          function InvalidTransformDataError(
              InvalidTransformDataErrorCode errorCode,
              bytes memory transformData
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("InvalidTransformDataError(uint8,bytes)")),
                  errorCode,
                  transformData
              );
          }
          // FillQuoteTransformer errors /////////////////////////////////////////////
          function IncompleteFillSellQuoteError(
              address sellToken,
              uint256 soldAmount,
              uint256 sellAmount
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("IncompleteFillSellQuoteError(address,uint256,uint256)")),
                  sellToken,
                  soldAmount,
                  sellAmount
              );
          }
          function IncompleteFillBuyQuoteError(
              address buyToken,
              uint256 boughtAmount,
              uint256 buyAmount
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("IncompleteFillBuyQuoteError(address,uint256,uint256)")),
                  buyToken,
                  boughtAmount,
                  buyAmount
              );
          }
          function InsufficientTakerTokenError(
              uint256 tokenBalance,
              uint256 tokensNeeded
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("InsufficientTakerTokenError(uint256,uint256)")),
                  tokenBalance,
                  tokensNeeded
              );
          }
          function InsufficientProtocolFeeError(
              uint256 ethBalance,
              uint256 ethNeeded
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("InsufficientProtocolFeeError(uint256,uint256)")),
                  ethBalance,
                  ethNeeded
              );
          }
          function InvalidERC20AssetDataError(
              bytes memory assetData
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("InvalidERC20AssetDataError(bytes)")),
                  assetData
              );
          }
          function InvalidTakerFeeTokenError(
              address token
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("InvalidTakerFeeTokenError(address)")),
                  token
              );
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibWalletRichErrors {
          // solhint-disable func-name-mixedcase
          function WalletExecuteCallFailedError(
              address wallet,
              address callTarget,
              bytes memory callData,
              uint256 callValue,
              bytes memory errorData
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("WalletExecuteCallFailedError(address,address,bytes,uint256,bytes)")),
                  wallet,
                  callTarget,
                  callData,
                  callValue,
                  errorData
              );
          }
          function WalletExecuteDelegateCallFailedError(
              address wallet,
              address callTarget,
              bytes memory callData,
              bytes memory errorData
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("WalletExecuteDelegateCallFailedError(address,address,bytes,bytes)")),
                  wallet,
                  callTarget,
                  callData,
                  errorData
              );
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/AuthorizableV06.sol";
      import "../errors/LibSpenderRichErrors.sol";
      import "./IAllowanceTarget.sol";
      /// @dev The allowance target for the TokenSpender feature.
      contract AllowanceTarget is
          IAllowanceTarget,
          AuthorizableV06
      {
          // solhint-disable no-unused-vars,indent,no-empty-blocks
          using LibRichErrorsV06 for bytes;
          /// @dev Execute an arbitrary call. Only an authority can call this.
          /// @param target The call target.
          /// @param callData The call data.
          /// @return resultData The data returned by the call.
          function executeCall(
              address payable target,
              bytes calldata callData
          )
              external
              override
              onlyAuthorized
              returns (bytes memory resultData)
          {
              bool success;
              (success, resultData) = target.call(callData);
              if (!success) {
                  resultData.rrevert();
              }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      import "./interfaces/IAuthorizableV06.sol";
      import "./errors/LibRichErrorsV06.sol";
      import "./errors/LibAuthorizableRichErrorsV06.sol";
      import "./OwnableV06.sol";
      // solhint-disable no-empty-blocks
      contract AuthorizableV06 is
          OwnableV06,
          IAuthorizableV06
      {
          /// @dev Only authorized addresses can invoke functions with this modifier.
          modifier onlyAuthorized {
              _assertSenderIsAuthorized();
              _;
          }
          // @dev Whether an address is authorized to call privileged functions.
          // @param 0 Address to query.
          // @return 0 Whether the address is authorized.
          mapping (address => bool) public override authorized;
          // @dev Whether an address is authorized to call privileged functions.
          // @param 0 Index of authorized address.
          // @return 0 Authorized address.
          address[] public override authorities;
          /// @dev Initializes the `owner` address.
          constructor()
              public
              OwnableV06()
          {}
          /// @dev Authorizes an address.
          /// @param target Address to authorize.
          function addAuthorizedAddress(address target)
              external
              override
              onlyOwner
          {
              _addAuthorizedAddress(target);
          }
          /// @dev Removes authorizion of an address.
          /// @param target Address to remove authorization from.
          function removeAuthorizedAddress(address target)
              external
              override
              onlyOwner
          {
              if (!authorized[target]) {
                  LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.TargetNotAuthorizedError(target));
              }
              for (uint256 i = 0; i < authorities.length; i++) {
                  if (authorities[i] == target) {
                      _removeAuthorizedAddressAtIndex(target, i);
                      break;
                  }
              }
          }
          /// @dev Removes authorizion of an address.
          /// @param target Address to remove authorization from.
          /// @param index Index of target in authorities array.
          function removeAuthorizedAddressAtIndex(
              address target,
              uint256 index
          )
              external
              override
              onlyOwner
          {
              _removeAuthorizedAddressAtIndex(target, index);
          }
          /// @dev Gets all authorized addresses.
          /// @return Array of authorized addresses.
          function getAuthorizedAddresses()
              external
              override
              view
              returns (address[] memory)
          {
              return authorities;
          }
          /// @dev Reverts if msg.sender is not authorized.
          function _assertSenderIsAuthorized()
              internal
              view
          {
              if (!authorized[msg.sender]) {
                  LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.SenderNotAuthorizedError(msg.sender));
              }
          }
          /// @dev Authorizes an address.
          /// @param target Address to authorize.
          function _addAuthorizedAddress(address target)
              internal
          {
              // Ensure that the target is not the zero address.
              if (target == address(0)) {
                  LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.ZeroCantBeAuthorizedError());
              }
              // Ensure that the target is not already authorized.
              if (authorized[target]) {
                  LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.TargetAlreadyAuthorizedError(target));
              }
              authorized[target] = true;
              authorities.push(target);
              emit AuthorizedAddressAdded(target, msg.sender);
          }
          /// @dev Removes authorizion of an address.
          /// @param target Address to remove authorization from.
          /// @param index Index of target in authorities array.
          function _removeAuthorizedAddressAtIndex(
              address target,
              uint256 index
          )
              internal
          {
              if (!authorized[target]) {
                  LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.TargetNotAuthorizedError(target));
              }
              if (index >= authorities.length) {
                  LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.IndexOutOfBoundsError(
                      index,
                      authorities.length
                  ));
              }
              if (authorities[index] != target) {
                  LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.AuthorizedAddressMismatchError(
                      authorities[index],
                      target
                  ));
              }
              delete authorized[target];
              authorities[index] = authorities[authorities.length - 1];
              authorities.pop();
              emit AuthorizedAddressRemoved(target, msg.sender);
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      import "./IOwnableV06.sol";
      interface IAuthorizableV06 is
          IOwnableV06
      {
          // Event logged when a new address is authorized.
          event AuthorizedAddressAdded(
              address indexed target,
              address indexed caller
          );
          // Event logged when a currently authorized address is unauthorized.
          event AuthorizedAddressRemoved(
              address indexed target,
              address indexed caller
          );
          /// @dev Authorizes an address.
          /// @param target Address to authorize.
          function addAuthorizedAddress(address target)
              external;
          /// @dev Removes authorizion of an address.
          /// @param target Address to remove authorization from.
          function removeAuthorizedAddress(address target)
              external;
          /// @dev Removes authorizion of an address.
          /// @param target Address to remove authorization from.
          /// @param index Index of target in authorities array.
          function removeAuthorizedAddressAtIndex(
              address target,
              uint256 index
          )
              external;
          /// @dev Gets all authorized addresses.
          /// @return authorizedAddresses Array of authorized addresses.
          function getAuthorizedAddresses()
              external
              view
              returns (address[] memory authorizedAddresses);
          /// @dev Whether an adderss is authorized to call privileged functions.
          /// @param addr Address to query.
          /// @return isAuthorized Whether the address is authorized.
          function authorized(address addr) external view returns (bool isAuthorized);
          /// @dev All addresseses authorized to call privileged functions.
          /// @param idx Index of authorized address.
          /// @return addr Authorized address.
          function authorities(uint256 idx) external view returns (address addr);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      interface IOwnableV06 {
          /// @dev Emitted by Ownable when ownership is transferred.
          /// @param previousOwner The previous owner of the contract.
          /// @param newOwner The new owner of the contract.
          event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
          /// @dev Transfers ownership of the contract to a new address.
          /// @param newOwner The address that will become the owner.
          function transferOwnership(address newOwner) external;
          /// @dev The owner of this contract.
          /// @return ownerAddress The owner address.
          function owner() external view returns (address ownerAddress);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibAuthorizableRichErrorsV06 {
          // bytes4(keccak256("AuthorizedAddressMismatchError(address,address)"))
          bytes4 internal constant AUTHORIZED_ADDRESS_MISMATCH_ERROR_SELECTOR =
              0x140a84db;
          // bytes4(keccak256("IndexOutOfBoundsError(uint256,uint256)"))
          bytes4 internal constant INDEX_OUT_OF_BOUNDS_ERROR_SELECTOR =
              0xe9f83771;
          // bytes4(keccak256("SenderNotAuthorizedError(address)"))
          bytes4 internal constant SENDER_NOT_AUTHORIZED_ERROR_SELECTOR =
              0xb65a25b9;
          // bytes4(keccak256("TargetAlreadyAuthorizedError(address)"))
          bytes4 internal constant TARGET_ALREADY_AUTHORIZED_ERROR_SELECTOR =
              0xde16f1a0;
          // bytes4(keccak256("TargetNotAuthorizedError(address)"))
          bytes4 internal constant TARGET_NOT_AUTHORIZED_ERROR_SELECTOR =
              0xeb5108a2;
          // bytes4(keccak256("ZeroCantBeAuthorizedError()"))
          bytes internal constant ZERO_CANT_BE_AUTHORIZED_ERROR_BYTES =
              hex"57654fe4";
          // solhint-disable func-name-mixedcase
          function AuthorizedAddressMismatchError(
              address authorized,
              address target
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  AUTHORIZED_ADDRESS_MISMATCH_ERROR_SELECTOR,
                  authorized,
                  target
              );
          }
          function IndexOutOfBoundsError(
              uint256 index,
              uint256 length
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  INDEX_OUT_OF_BOUNDS_ERROR_SELECTOR,
                  index,
                  length
              );
          }
          function SenderNotAuthorizedError(address sender)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  SENDER_NOT_AUTHORIZED_ERROR_SELECTOR,
                  sender
              );
          }
          function TargetAlreadyAuthorizedError(address target)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  TARGET_ALREADY_AUTHORIZED_ERROR_SELECTOR,
                  target
              );
          }
          function TargetNotAuthorizedError(address target)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  TARGET_NOT_AUTHORIZED_ERROR_SELECTOR,
                  target
              );
          }
          function ZeroCantBeAuthorizedError()
              internal
              pure
              returns (bytes memory)
          {
              return ZERO_CANT_BE_AUTHORIZED_ERROR_BYTES;
          }
      }
      /*
        Copyright 2019 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      import "./interfaces/IOwnableV06.sol";
      import "./errors/LibRichErrorsV06.sol";
      import "./errors/LibOwnableRichErrorsV06.sol";
      contract OwnableV06 is
          IOwnableV06
      {
          /// @dev The owner of this contract.
          /// @return 0 The owner address.
          address public override owner;
          constructor() public {
              owner = msg.sender;
          }
          modifier onlyOwner() {
              _assertSenderIsOwner();
              _;
          }
          /// @dev Change the owner of this contract.
          /// @param newOwner New owner address.
          function transferOwnership(address newOwner)
              public
              override
              onlyOwner
          {
              if (newOwner == address(0)) {
                  LibRichErrorsV06.rrevert(LibOwnableRichErrorsV06.TransferOwnerToZeroError());
              } else {
                  owner = newOwner;
                  emit OwnershipTransferred(msg.sender, newOwner);
              }
          }
          function _assertSenderIsOwner()
              internal
              view
          {
              if (msg.sender != owner) {
                  LibRichErrorsV06.rrevert(LibOwnableRichErrorsV06.OnlyOwnerError(
                      msg.sender,
                      owner
                  ));
              }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibOwnableRichErrorsV06 {
          // bytes4(keccak256("OnlyOwnerError(address,address)"))
          bytes4 internal constant ONLY_OWNER_ERROR_SELECTOR =
              0x1de45ad1;
          // bytes4(keccak256("TransferOwnerToZeroError()"))
          bytes internal constant TRANSFER_OWNER_TO_ZERO_ERROR_BYTES =
              hex"e69edc3e";
          // solhint-disable func-name-mixedcase
          function OnlyOwnerError(
              address sender,
              address owner
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  ONLY_OWNER_ERROR_SELECTOR,
                  sender,
                  owner
              );
          }
          function TransferOwnerToZeroError()
              internal
              pure
              returns (bytes memory)
          {
              return TRANSFER_OWNER_TO_ZERO_ERROR_BYTES;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/interfaces/IAuthorizableV06.sol";
      /// @dev The allowance target for the TokenSpender feature.
      interface IAllowanceTarget is
          IAuthorizableV06
      {
          /// @dev Execute an arbitrary call. Only an authority can call this.
          /// @param target The call target.
          /// @param callData The call data.
          /// @return resultData The data returned by the call.
          function executeCall(
              address payable target,
              bytes calldata callData
          )
              external
              returns (bytes memory resultData);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/errors/LibOwnableRichErrorsV06.sol";
      import "../errors/LibWalletRichErrors.sol";
      import "./IFlashWallet.sol";
      /// @dev A contract that can execute arbitrary calls from its owner.
      contract FlashWallet is
          IFlashWallet
      {
          // solhint-disable no-unused-vars,indent,no-empty-blocks
          using LibRichErrorsV06 for bytes;
          // solhint-disable
          /// @dev Store the owner/deployer as an immutable to make this contract stateless.
          address public override immutable owner;
          // solhint-enable
          constructor() public {
              // The deployer is the owner.
              owner = msg.sender;
          }
          /// @dev Allows only the (immutable) owner to call a function.
          modifier onlyOwner() virtual {
              if (msg.sender != owner) {
                  LibOwnableRichErrorsV06.OnlyOwnerError(
                      msg.sender,
                      owner
                  ).rrevert();
              }
              _;
          }
          /// @dev Execute an arbitrary call. Only an authority can call this.
          /// @param target The call target.
          /// @param callData The call data.
          /// @param value Ether to attach to the call.
          /// @return resultData The data returned by the call.
          function executeCall(
              address payable target,
              bytes calldata callData,
              uint256 value
          )
              external
              payable
              override
              onlyOwner
              returns (bytes memory resultData)
          {
              bool success;
              (success, resultData) = target.call{value: value}(callData);
              if (!success) {
                  LibWalletRichErrors
                      .WalletExecuteCallFailedError(
                          address(this),
                          target,
                          callData,
                          value,
                          resultData
                      )
                      .rrevert();
              }
          }
          /// @dev Execute an arbitrary delegatecall, in the context of this puppet.
          ///      Only an authority can call this.
          /// @param target The call target.
          /// @param callData The call data.
          /// @return resultData The data returned by the call.
          function executeDelegateCall(
              address payable target,
              bytes calldata callData
          )
              external
              payable
              override
              onlyOwner
              returns (bytes memory resultData)
          {
              bool success;
              (success, resultData) = target.delegatecall(callData);
              if (!success) {
                  LibWalletRichErrors
                      .WalletExecuteDelegateCallFailedError(
                          address(this),
                          target,
                          callData,
                          resultData
                      )
                      .rrevert();
              }
          }
          // solhint-disable
          /// @dev Allows this contract to receive ether.
          receive() external override payable {}
          // solhint-enable
          /// @dev Signal support for receiving ERC1155 tokens.
          /// @param interfaceID The interface ID, as per ERC-165 rules.
          /// @return hasSupport `true` if this contract supports an ERC-165 interface.
          function supportsInterface(bytes4 interfaceID)
              external
              pure
              returns (bool hasSupport)
          {
              return  interfaceID == this.supportsInterface.selector ||
                      interfaceID == this.onERC1155Received.selector ^ this.onERC1155BatchReceived.selector ||
                      interfaceID == this.tokenFallback.selector;
          }
          ///  @dev Allow this contract to receive ERC1155 tokens.
          ///  @return success  `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
          function onERC1155Received(
              address, // operator,
              address, // from,
              uint256, // id,
              uint256, // value,
              bytes calldata //data
          )
              external
              pure
              returns (bytes4 success)
          {
              return this.onERC1155Received.selector;
          }
          ///  @dev Allow this contract to receive ERC1155 tokens.
          ///  @return success  `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
          function onERC1155BatchReceived(
              address, // operator,
              address, // from,
              uint256[] calldata, // ids,
              uint256[] calldata, // values,
              bytes calldata // data
          )
              external
              pure
              returns (bytes4 success)
          {
              return this.onERC1155BatchReceived.selector;
          }
          /// @dev Allows this contract to receive ERC223 tokens.
          function tokenFallback(
              address, // from,
              uint256, // value,
              bytes calldata // value
          )
              external
              pure
          {}
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/interfaces/IOwnableV06.sol";
      /// @dev A contract that can execute arbitrary calls from its owner.
      interface IFlashWallet {
          /// @dev Execute an arbitrary call. Only an authority can call this.
          /// @param target The call target.
          /// @param callData The call data.
          /// @param value Ether to attach to the call.
          /// @return resultData The data returned by the call.
          function executeCall(
              address payable target,
              bytes calldata callData,
              uint256 value
          )
              external
              payable
              returns (bytes memory resultData);
          /// @dev Execute an arbitrary delegatecall, in the context of this puppet.
          ///      Only an authority can call this.
          /// @param target The call target.
          /// @param callData The call data.
          /// @return resultData The data returned by the call.
          function executeDelegateCall(
              address payable target,
              bytes calldata callData
          )
              external
              payable
              returns (bytes memory resultData);
          /// @dev Allows the puppet to receive ETH.
          receive() external payable;
          /// @dev Fetch the immutable owner/deployer of this contract.
          /// @return owner_ The immutable owner/deployer/
          function owner() external view returns (address owner_);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/AuthorizableV06.sol";
      /// @dev A contract with a `die()` function.
      interface IKillable {
          function die() external;
      }
      /// @dev Deployer contract for ERC20 transformers.
      ///      Only authorities may call `deploy()` and `kill()`.
      contract TransformerDeployer is
          AuthorizableV06
      {
          /// @dev Emitted when a contract is deployed via `deploy()`.
          /// @param deployedAddress The address of the deployed contract.
          /// @param nonce The deployment nonce.
          /// @param sender The caller of `deploy()`.
          event Deployed(address deployedAddress, uint256 nonce, address sender);
          /// @dev Emitted when a contract is killed via `kill()`.
          /// @param target The address of the contract being killed..
          /// @param sender The caller of `kill()`.
          event Killed(address target, address sender);
          // @dev The current nonce of this contract.
          uint256 public nonce = 1;
          // @dev Mapping of deployed contract address to deployment nonce.
          mapping (address => uint256) public toDeploymentNonce;
          /// @dev Create this contract and register authorities.
          constructor(address[] memory authorities) public {
              for (uint256 i = 0; i < authorities.length; ++i) {
                  _addAuthorizedAddress(authorities[i]);
              }
          }
          /// @dev Deploy a new contract. Only callable by an authority.
          ///      Any attached ETH will also be forwarded.
          function deploy(bytes memory bytecode)
              public
              payable
              onlyAuthorized
              returns (address deployedAddress)
          {
              uint256 deploymentNonce = nonce;
              nonce += 1;
              assembly {
                  deployedAddress := create(callvalue(), add(bytecode, 32), mload(bytecode))
              }
              toDeploymentNonce[deployedAddress] = deploymentNonce;
              emit Deployed(deployedAddress, deploymentNonce, msg.sender);
          }
          /// @dev Call `die()` on a contract. Only callable by an authority.
          function kill(IKillable target)
              public
              onlyAuthorized
          {
              target.die();
              emit Killed(address(target), msg.sender);
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      /// @dev Basic interface for a feature contract.
      interface IFeature {
          // solhint-disable func-name-mixedcase
          /// @dev The name of this feature set.
          function FEATURE_NAME() external view returns (string memory name);
          /// @dev The version of this feature set.
          function FEATURE_VERSION() external view returns (uint256 version);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/interfaces/IOwnableV06.sol";
      // solhint-disable no-empty-blocks
      /// @dev Owner management and migration features.
      interface IOwnable is
          IOwnableV06
      {
          /// @dev Emitted when `migrate()` is called.
          /// @param caller The caller of `migrate()`.
          /// @param migrator The migration contract.
          /// @param newOwner The address of the new owner.
          event Migrated(address caller, address migrator, address newOwner);
          /// @dev Execute a migration function in the context of the ZeroEx contract.
          ///      The result of the function being called should be the magic bytes
          ///      0x2c64c5ef (`keccack('MIGRATE_SUCCESS')`). Only callable by the owner.
          ///      The owner will be temporarily set to `address(this)` inside the call.
          ///      Before returning, the owner will be set to `newOwner`.
          /// @param target The migrator contract address.
          /// @param newOwner The address of the new owner.
          /// @param data The call data.
          function migrate(address target, bytes calldata data, address newOwner) external;
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      /// @dev Basic registry management features.
      interface ISimpleFunctionRegistry {
          /// @dev A function implementation was updated via `extend()` or `rollback()`.
          /// @param selector The function selector.
          /// @param oldImpl The implementation contract address being replaced.
          /// @param newImpl The replacement implementation contract address.
          event ProxyFunctionUpdated(bytes4 indexed selector, address oldImpl, address newImpl);
          /// @dev Roll back to a prior implementation of a function.
          /// @param selector The function selector.
          /// @param targetImpl The address of an older implementation of the function.
          function rollback(bytes4 selector, address targetImpl) external;
          /// @dev Register or replace a function.
          /// @param selector The function selector.
          /// @param impl The implementation contract for the function.
          function extend(bytes4 selector, address impl) external;
          /// @dev Retrieve the length of the rollback history for a function.
          /// @param selector The function selector.
          /// @return rollbackLength The number of items in the rollback history for
          ///         the function.
          function getRollbackLength(bytes4 selector)
              external
              view
              returns (uint256 rollbackLength);
          /// @dev Retrieve an entry in the rollback history for a function.
          /// @param selector The function selector.
          /// @param idx The index in the rollback history.
          /// @return impl An implementation address for the function at
          ///         index `idx`.
          function getRollbackEntryAtIndex(bytes4 selector, uint256 idx)
              external
              view
              returns (address impl);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      /// @dev Feature that allows spending token allowances.
      interface ITokenSpender {
          /// @dev Transfers ERC20 tokens from `owner` to `to`.
          ///      Only callable from within.
          /// @param token The token to spend.
          /// @param owner The owner of the tokens.
          /// @param to The recipient of the tokens.
          /// @param amount The amount of `token` to transfer.
          function _spendERC20Tokens(
              IERC20TokenV06 token,
              address owner,
              address to,
              uint256 amount
          )
              external;
          /// @dev Gets the maximum amount of an ERC20 token `token` that can be
          ///      pulled from `owner`.
          /// @param token The token to spend.
          /// @param owner The owner of the tokens.
          /// @return amount The amount of tokens that can be pulled.
          function getSpendableERC20BalanceOf(IERC20TokenV06 token, address owner)
              external
              view
              returns (uint256 amount);
          /// @dev Get the address of the allowance target.
          /// @return target The target of token allowances.
          function getAllowanceTarget() external view returns (address target);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      interface IERC20TokenV06 {
          // solhint-disable no-simple-event-func-name
          event Transfer(
              address indexed from,
              address indexed to,
              uint256 value
          );
          event Approval(
              address indexed owner,
              address indexed spender,
              uint256 value
          );
          /// @dev send `value` token to `to` from `msg.sender`
          /// @param to The address of the recipient
          /// @param value The amount of token to be transferred
          /// @return True if transfer was successful
          function transfer(address to, uint256 value)
              external
              returns (bool);
          /// @dev send `value` token to `to` from `from` on the condition it is approved by `from`
          /// @param from The address of the sender
          /// @param to The address of the recipient
          /// @param value The amount of token to be transferred
          /// @return True if transfer was successful
          function transferFrom(
              address from,
              address to,
              uint256 value
          )
              external
              returns (bool);
          /// @dev `msg.sender` approves `spender` to spend `value` tokens
          /// @param spender The address of the account able to transfer the tokens
          /// @param value The amount of wei to be approved for transfer
          /// @return Always true if the call has enough gas to complete execution
          function approve(address spender, uint256 value)
              external
              returns (bool);
          /// @dev Query total supply of token
          /// @return Total supply of token
          function totalSupply()
              external
              view
              returns (uint256);
          /// @dev Get the balance of `owner`.
          /// @param owner The address from which the balance will be retrieved
          /// @return Balance of owner
          function balanceOf(address owner)
              external
              view
              returns (uint256);
          /// @dev Get the allowance for `spender` to spend from `owner`.
          /// @param owner The address of the account owning tokens
          /// @param spender The address of the account able to transfer the tokens
          /// @return Amount of remaining tokens allowed to spent
          function allowance(address owner, address spender)
              external
              view
              returns (uint256);
          /// @dev Get the number of decimals this token has.
          function decimals()
              external
              view
              returns (uint8);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "../transformers/IERC20Transformer.sol";
      import "../external/IFlashWallet.sol";
      /// @dev Feature to composably transform between ERC20 tokens.
      interface ITransformERC20 {
          /// @dev Defines a transformation to run in `transformERC20()`.
          struct Transformation {
              // The deployment nonce for the transformer.
              // The address of the transformer contract will be derived from this
              // value.
              uint32 deploymentNonce;
              // Arbitrary data to pass to the transformer.
              bytes data;
          }
          /// @dev Raised upon a successful `transformERC20`.
          /// @param taker The taker (caller) address.
          /// @param inputToken The token being provided by the taker.
          ///        If `0xeee...`, ETH is implied and should be provided with the call.`
          /// @param outputToken The token to be acquired by the taker.
          ///        `0xeee...` implies ETH.
          /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
          /// @param outputTokenAmount The amount of `outputToken` received by the taker.
          event TransformedERC20(
              address indexed taker,
              address inputToken,
              address outputToken,
              uint256 inputTokenAmount,
              uint256 outputTokenAmount
          );
          /// @dev Raised when `setTransformerDeployer()` is called.
          /// @param transformerDeployer The new deployer address.
          event TransformerDeployerUpdated(address transformerDeployer);
          /// @dev Replace the allowed deployer for transformers.
          ///      Only callable by the owner.
          /// @param transformerDeployer The address of the trusted deployer for transformers.
          function setTransformerDeployer(address transformerDeployer)
              external;
          /// @dev Deploy a new flash wallet instance and replace the current one with it.
          ///      Useful if we somehow break the current wallet instance.
          ///      Anyone can call this.
          /// @return wallet The new wallet instance.
          function createTransformWallet()
              external
              returns (IFlashWallet wallet);
          /// @dev Executes a series of transformations to convert an ERC20 `inputToken`
          ///      to an ERC20 `outputToken`.
          /// @param inputToken The token being provided by the sender.
          ///        If `0xeee...`, ETH is implied and should be provided with the call.`
          /// @param outputToken The token to be acquired by the sender.
          ///        `0xeee...` implies ETH.
          /// @param inputTokenAmount The amount of `inputToken` to take from the sender.
          /// @param minOutputTokenAmount The minimum amount of `outputToken` the sender
          ///        must receive for the entire transformation to succeed.
          /// @param transformations The transformations to execute on the token balance(s)
          ///        in sequence.
          /// @return outputTokenAmount The amount of `outputToken` received by the sender.
          function transformERC20(
              IERC20TokenV06 inputToken,
              IERC20TokenV06 outputToken,
              uint256 inputTokenAmount,
              uint256 minOutputTokenAmount,
              Transformation[] calldata transformations
          )
              external
              payable
              returns (uint256 outputTokenAmount);
          /// @dev Internal version of `transformERC20()`. Only callable from within.
          /// @param callDataHash Hash of the ingress calldata.
          /// @param taker The taker address.
          /// @param inputToken The token being provided by the taker.
          ///        If `0xeee...`, ETH is implied and should be provided with the call.`
          /// @param outputToken The token to be acquired by the taker.
          ///        `0xeee...` implies ETH.
          /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
          /// @param minOutputTokenAmount The minimum amount of `outputToken` the taker
          ///        must receive for the entire transformation to succeed.
          /// @param transformations The transformations to execute on the token balance(s)
          ///        in sequence.
          /// @return outputTokenAmount The amount of `outputToken` received by the taker.
          function _transformERC20(
              bytes32 callDataHash,
              address payable taker,
              IERC20TokenV06 inputToken,
              IERC20TokenV06 outputToken,
              uint256 inputTokenAmount,
              uint256 minOutputTokenAmount,
              Transformation[] calldata transformations
          )
              external
              payable
              returns (uint256 outputTokenAmount);
          /// @dev Return the current wallet instance that will serve as the execution
          ///      context for transformations.
          /// @return wallet The wallet instance.
          function getTransformWallet()
              external
              view
              returns (IFlashWallet wallet);
          /// @dev Return the allowed deployer for transformers.
          /// @return deployer The transform deployer address.
          function getTransformerDeployer()
              external
              view
              returns (address deployer);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      /// @dev A transformation callback used in `TransformERC20.transformERC20()`.
      interface IERC20Transformer {
          /// @dev Called from `TransformERC20.transformERC20()`. This will be
          ///      delegatecalled in the context of the FlashWallet instance being used.
          /// @param callDataHash The hash of the `TransformERC20.transformERC20()` calldata.
          /// @param taker The taker address (caller of `TransformERC20.transformERC20()`).
          /// @param data Arbitrary data to pass to the transformer.
          /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
          function transform(
              bytes32 callDataHash,
              address payable taker,
              bytes calldata data
          )
              external
              returns (bytes4 success);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "../fixins/FixinCommon.sol";
      import "../errors/LibOwnableRichErrors.sol";
      import "../storage/LibOwnableStorage.sol";
      import "../migrations/LibBootstrap.sol";
      import "../migrations/LibMigrate.sol";
      import "./IFeature.sol";
      import "./IOwnable.sol";
      import "./SimpleFunctionRegistry.sol";
      /// @dev Owner management features.
      contract Ownable is
          IFeature,
          IOwnable,
          FixinCommon
      {
          // solhint-disable
          /// @dev Name of this feature.
          string public constant override FEATURE_NAME = "Ownable";
          /// @dev Version of this feature.
          uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
          /// @dev The deployed address of this contract.
          address immutable private _implementation;
          // solhint-enable
          using LibRichErrorsV06 for bytes;
          constructor() public {
              _implementation = address(this);
          }
          /// @dev Initializes this feature. The intial owner will be set to this (ZeroEx)
          ///      to allow the bootstrappers to call `extend()`. Ownership should be
          ///      transferred to the real owner by the bootstrapper after
          ///      bootstrapping is complete.
          /// @return success Magic bytes if successful.
          function bootstrap() external returns (bytes4 success) {
              // Set the owner to ourselves to allow bootstrappers to call `extend()`.
              LibOwnableStorage.getStorage().owner = address(this);
              // Register feature functions.
              SimpleFunctionRegistry(address(this))._extendSelf(this.transferOwnership.selector, _implementation);
              SimpleFunctionRegistry(address(this))._extendSelf(this.owner.selector, _implementation);
              SimpleFunctionRegistry(address(this))._extendSelf(this.migrate.selector, _implementation);
              return LibBootstrap.BOOTSTRAP_SUCCESS;
          }
          /// @dev Change the owner of this contract.
          ///      Only directly callable by the owner.
          /// @param newOwner New owner address.
          function transferOwnership(address newOwner)
              external
              override
              onlyOwner
          {
              LibOwnableStorage.Storage storage proxyStor = LibOwnableStorage.getStorage();
              if (newOwner == address(0)) {
                  LibOwnableRichErrors.TransferOwnerToZeroError().rrevert();
              } else {
                  proxyStor.owner = newOwner;
                  emit OwnershipTransferred(msg.sender, newOwner);
              }
          }
          /// @dev Execute a migration function in the context of the ZeroEx contract.
          ///      The result of the function being called should be the magic bytes
          ///      0x2c64c5ef (`keccack('MIGRATE_SUCCESS')`). Only callable by the owner.
          ///      Temporarily sets the owner to ourselves so we can perform admin functions.
          ///      Before returning, the owner will be set to `newOwner`.
          /// @param target The migrator contract address.
          /// @param data The call data.
          /// @param newOwner The address of the new owner.
          function migrate(address target, bytes calldata data, address newOwner)
              external
              override
              onlyOwner
          {
              if (newOwner == address(0)) {
                  LibOwnableRichErrors.TransferOwnerToZeroError().rrevert();
              }
              LibOwnableStorage.Storage storage stor = LibOwnableStorage.getStorage();
              // The owner will be temporarily set to `address(this)` inside the call.
              stor.owner = address(this);
              // Perform the migration.
              LibMigrate.delegatecallMigrateFunction(target, data);
              // Update the owner.
              stor.owner = newOwner;
              emit Migrated(msg.sender, target, newOwner);
          }
          /// @dev Get the owner of this contract.
          /// @return owner_ The owner of this contract.
          function owner() external override view returns (address owner_) {
              return LibOwnableStorage.getStorage().owner;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "../errors/LibCommonRichErrors.sol";
      import "../errors/LibOwnableRichErrors.sol";
      import "../features/IOwnable.sol";
      /// @dev Common feature utilities.
      contract FixinCommon {
          using LibRichErrorsV06 for bytes;
          /// @dev The caller must be this contract.
          modifier onlySelf() virtual {
              if (msg.sender != address(this)) {
                  LibCommonRichErrors.OnlyCallableBySelfError(msg.sender).rrevert();
              }
              _;
          }
          /// @dev The caller of this function must be the owner.
          modifier onlyOwner() virtual {
              {
                  address owner = IOwnable(address(this)).owner();
                  if (msg.sender != owner) {
                      LibOwnableRichErrors.OnlyOwnerError(
                          msg.sender,
                          owner
                      ).rrevert();
                  }
              }
              _;
          }
          /// @dev Encode a feature version as a `uint256`.
          /// @param major The major version number of the feature.
          /// @param minor The minor version number of the feature.
          /// @param revision The revision number of the feature.
          /// @return encodedVersion The encoded version number.
          function _encodeVersion(uint32 major, uint32 minor, uint32 revision)
              internal
              pure
              returns (uint256 encodedVersion)
          {
              return (major << 64) | (minor << 32) | revision;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "./LibStorage.sol";
      /// @dev Storage helpers for the `Ownable` feature.
      library LibOwnableStorage {
          /// @dev Storage bucket for this feature.
          struct Storage {
              // The owner of this contract.
              address owner;
          }
          /// @dev Get the storage bucket for this contract.
          function getStorage() internal pure returns (Storage storage stor) {
              uint256 storageSlot = LibStorage.getStorageSlot(
                  LibStorage.StorageId.Ownable
              );
              // Dip into assembly to change the slot pointed to by the local
              // variable `stor`.
              // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
              assembly { stor_slot := storageSlot }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "../errors/LibOwnableRichErrors.sol";
      library LibMigrate {
          /// @dev Magic bytes returned by a migrator to indicate success.
          ///      This is `keccack('MIGRATE_SUCCESS')`.
          bytes4 internal constant MIGRATE_SUCCESS = 0x2c64c5ef;
          using LibRichErrorsV06 for bytes;
          /// @dev Perform a delegatecall and ensure it returns the magic bytes.
          /// @param target The call target.
          /// @param data The call data.
          function delegatecallMigrateFunction(
              address target,
              bytes memory data
          )
              internal
          {
              (bool success, bytes memory resultData) = target.delegatecall(data);
              if (!success ||
                  resultData.length != 32 ||
                  abi.decode(resultData, (bytes4)) != MIGRATE_SUCCESS)
              {
                  LibOwnableRichErrors.MigrateCallFailedError(target, resultData).rrevert();
              }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "../fixins/FixinCommon.sol";
      import "../storage/LibProxyStorage.sol";
      import "../storage/LibSimpleFunctionRegistryStorage.sol";
      import "../errors/LibSimpleFunctionRegistryRichErrors.sol";
      import "../migrations/LibBootstrap.sol";
      import "./IFeature.sol";
      import "./ISimpleFunctionRegistry.sol";
      /// @dev Basic registry management features.
      contract SimpleFunctionRegistry is
          IFeature,
          ISimpleFunctionRegistry,
          FixinCommon
      {
          // solhint-disable
          /// @dev Name of this feature.
          string public constant override FEATURE_NAME = "SimpleFunctionRegistry";
          /// @dev Version of this feature.
          uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
          /// @dev The deployed address of this contract.
          address private immutable _implementation;
          // solhint-enable
          using LibRichErrorsV06 for bytes;
          constructor() public {
              _implementation = address(this);
          }
          /// @dev Initializes this feature, registering its own functions.
          /// @return success Magic bytes if successful.
          function bootstrap()
              external
              returns (bytes4 success)
          {
              // Register the registration functions (inception vibes).
              _extend(this.extend.selector, _implementation);
              _extend(this._extendSelf.selector, _implementation);
              // Register the rollback function.
              _extend(this.rollback.selector, _implementation);
              // Register getters.
              _extend(this.getRollbackLength.selector, _implementation);
              _extend(this.getRollbackEntryAtIndex.selector, _implementation);
              return LibBootstrap.BOOTSTRAP_SUCCESS;
          }
          /// @dev Roll back to a prior implementation of a function.
          ///      Only directly callable by an authority.
          /// @param selector The function selector.
          /// @param targetImpl The address of an older implementation of the function.
          function rollback(bytes4 selector, address targetImpl)
              external
              override
              onlyOwner
          {
              (
                  LibSimpleFunctionRegistryStorage.Storage storage stor,
                  LibProxyStorage.Storage storage proxyStor
              ) = _getStorages();
              address currentImpl = proxyStor.impls[selector];
              if (currentImpl == targetImpl) {
                  // Do nothing if already at targetImpl.
                  return;
              }
              // Walk history backwards until we find the target implementation.
              address[] storage history = stor.implHistory[selector];
              uint256 i = history.length;
              for (; i > 0; --i) {
                  address impl = history[i - 1];
                  history.pop();
                  if (impl == targetImpl) {
                      break;
                  }
              }
              if (i == 0) {
                  LibSimpleFunctionRegistryRichErrors.NotInRollbackHistoryError(
                      selector,
                      targetImpl
                  ).rrevert();
              }
              proxyStor.impls[selector] = targetImpl;
              emit ProxyFunctionUpdated(selector, currentImpl, targetImpl);
          }
          /// @dev Register or replace a function.
          ///      Only directly callable by an authority.
          /// @param selector The function selector.
          /// @param impl The implementation contract for the function.
          function extend(bytes4 selector, address impl)
              external
              override
              onlyOwner
          {
              _extend(selector, impl);
          }
          /// @dev Register or replace a function.
          ///      Only callable from within.
          ///      This function is only used during the bootstrap process and
          ///      should be deregistered by the deployer after bootstrapping is
          ///      complete.
          /// @param selector The function selector.
          /// @param impl The implementation contract for the function.
          function _extendSelf(bytes4 selector, address impl)
              external
              onlySelf
          {
              _extend(selector, impl);
          }
          /// @dev Retrieve the length of the rollback history for a function.
          /// @param selector The function selector.
          /// @return rollbackLength The number of items in the rollback history for
          ///         the function.
          function getRollbackLength(bytes4 selector)
              external
              override
              view
              returns (uint256 rollbackLength)
          {
              return LibSimpleFunctionRegistryStorage.getStorage().implHistory[selector].length;
          }
          /// @dev Retrieve an entry in the rollback history for a function.
          /// @param selector The function selector.
          /// @param idx The index in the rollback history.
          /// @return impl An implementation address for the function at
          ///         index `idx`.
          function getRollbackEntryAtIndex(bytes4 selector, uint256 idx)
              external
              override
              view
              returns (address impl)
          {
              return LibSimpleFunctionRegistryStorage.getStorage().implHistory[selector][idx];
          }
          /// @dev Register or replace a function.
          /// @param selector The function selector.
          /// @param impl The implementation contract for the function.
          function _extend(bytes4 selector, address impl)
              private
          {
              (
                  LibSimpleFunctionRegistryStorage.Storage storage stor,
                  LibProxyStorage.Storage storage proxyStor
              ) = _getStorages();
              address oldImpl = proxyStor.impls[selector];
              address[] storage history = stor.implHistory[selector];
              history.push(oldImpl);
              proxyStor.impls[selector] = impl;
              emit ProxyFunctionUpdated(selector, oldImpl, impl);
          }
          /// @dev Get the storage buckets for this feature and the proxy.
          /// @return stor Storage bucket for this feature.
          /// @return proxyStor age bucket for the proxy.
          function _getStorages()
              private
              pure
              returns (
                  LibSimpleFunctionRegistryStorage.Storage storage stor,
                  LibProxyStorage.Storage storage proxyStor
              )
          {
              return (
                  LibSimpleFunctionRegistryStorage.getStorage(),
                  LibProxyStorage.getStorage()
              );
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "./LibStorage.sol";
      /// @dev Storage helpers for the `SimpleFunctionRegistry` feature.
      library LibSimpleFunctionRegistryStorage {
          /// @dev Storage bucket for this feature.
          struct Storage {
              // Mapping of function selector -> implementation history.
              mapping(bytes4 => address[]) implHistory;
          }
          /// @dev Get the storage bucket for this contract.
          function getStorage() internal pure returns (Storage storage stor) {
              uint256 storageSlot = LibStorage.getStorageSlot(
                  LibStorage.StorageId.SimpleFunctionRegistry
              );
              // Dip into assembly to change the slot pointed to by the local
              // variable `stor`.
              // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
              assembly { stor_slot := storageSlot }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
      import "../errors/LibSpenderRichErrors.sol";
      import "../fixins/FixinCommon.sol";
      import "../migrations/LibMigrate.sol";
      import "../external/IAllowanceTarget.sol";
      import "../storage/LibTokenSpenderStorage.sol";
      import "./ITokenSpender.sol";
      import "./IFeature.sol";
      import "./ISimpleFunctionRegistry.sol";
      /// @dev Feature that allows spending token allowances.
      contract TokenSpender is
          IFeature,
          ITokenSpender,
          FixinCommon
      {
          // solhint-disable
          /// @dev Name of this feature.
          string public constant override FEATURE_NAME = "TokenSpender";
          /// @dev Version of this feature.
          uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
          /// @dev The implementation address of this feature.
          address private immutable _implementation;
          // solhint-enable
          using LibRichErrorsV06 for bytes;
          constructor() public {
              _implementation = address(this);
          }
          /// @dev Initialize and register this feature. Should be delegatecalled
          ///      into during a `Migrate.migrate()`.
          /// @param allowanceTarget An `allowanceTarget` instance, configured to have
          ///        the ZeroeEx contract as an authority.
          /// @return success `MIGRATE_SUCCESS` on success.
          function migrate(IAllowanceTarget allowanceTarget) external returns (bytes4 success) {
              LibTokenSpenderStorage.getStorage().allowanceTarget = allowanceTarget;
              ISimpleFunctionRegistry(address(this))
                  .extend(this.getAllowanceTarget.selector, _implementation);
              ISimpleFunctionRegistry(address(this))
                  .extend(this._spendERC20Tokens.selector, _implementation);
              ISimpleFunctionRegistry(address(this))
                  .extend(this.getSpendableERC20BalanceOf.selector, _implementation);
              return LibMigrate.MIGRATE_SUCCESS;
          }
          /// @dev Transfers ERC20 tokens from `owner` to `to`. Only callable from within.
          /// @param token The token to spend.
          /// @param owner The owner of the tokens.
          /// @param to The recipient of the tokens.
          /// @param amount The amount of `token` to transfer.
          function _spendERC20Tokens(
              IERC20TokenV06 token,
              address owner,
              address to,
              uint256 amount
          )
              external
              override
              onlySelf
          {
              IAllowanceTarget spender = LibTokenSpenderStorage.getStorage().allowanceTarget;
              // Have the allowance target execute an ERC20 `transferFrom()`.
              (bool didSucceed, bytes memory resultData) = address(spender).call(
                  abi.encodeWithSelector(
                      IAllowanceTarget.executeCall.selector,
                      address(token),
                      abi.encodeWithSelector(
                          IERC20TokenV06.transferFrom.selector,
                          owner,
                          to,
                          amount
                      )
                  )
              );
              if (didSucceed) {
                  resultData = abi.decode(resultData, (bytes));
              }
              if (!didSucceed || !LibERC20TokenV06.isSuccessfulResult(resultData)) {
                  LibSpenderRichErrors.SpenderERC20TransferFromFailedError(
                      address(token),
                      owner,
                      to,
                      amount,
                      resultData
                  ).rrevert();
              }
          }
          /// @dev Gets the maximum amount of an ERC20 token `token` that can be
          ///      pulled from `owner` by the token spender.
          /// @param token The token to spend.
          /// @param owner The owner of the tokens.
          /// @return amount The amount of tokens that can be pulled.
          function getSpendableERC20BalanceOf(IERC20TokenV06 token, address owner)
              external
              override
              view
              returns (uint256 amount)
          {
              return LibSafeMathV06.min256(
                  token.allowance(owner, address(LibTokenSpenderStorage.getStorage().allowanceTarget)),
                  token.balanceOf(owner)
              );
          }
          /// @dev Get the address of the allowance target.
          /// @return target The target of token allowances.
          function getAllowanceTarget()
              external
              override
              view
              returns (address target)
          {
              return address(LibTokenSpenderStorage.getStorage().allowanceTarget);
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      import "./errors/LibRichErrorsV06.sol";
      import "./errors/LibSafeMathRichErrorsV06.sol";
      library LibSafeMathV06 {
          function safeMul(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              if (a == 0) {
                  return 0;
              }
              uint256 c = a * b;
              if (c / a != b) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                      a,
                      b
                  ));
              }
              return c;
          }
          function safeDiv(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              if (b == 0) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                      a,
                      b
                  ));
              }
              uint256 c = a / b;
              return c;
          }
          function safeSub(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              if (b > a) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                      a,
                      b
                  ));
              }
              return a - b;
          }
          function safeAdd(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              uint256 c = a + b;
              if (c < a) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                      a,
                      b
                  ));
              }
              return c;
          }
          function max256(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              return a >= b ? a : b;
          }
          function min256(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              return a < b ? a : b;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibSafeMathRichErrorsV06 {
          // bytes4(keccak256("Uint256BinOpError(uint8,uint256,uint256)"))
          bytes4 internal constant UINT256_BINOP_ERROR_SELECTOR =
              0xe946c1bb;
          // bytes4(keccak256("Uint256DowncastError(uint8,uint256)"))
          bytes4 internal constant UINT256_DOWNCAST_ERROR_SELECTOR =
              0xc996af7b;
          enum BinOpErrorCodes {
              ADDITION_OVERFLOW,
              MULTIPLICATION_OVERFLOW,
              SUBTRACTION_UNDERFLOW,
              DIVISION_BY_ZERO
          }
          enum DowncastErrorCodes {
              VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT32,
              VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT64,
              VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT96
          }
          // solhint-disable func-name-mixedcase
          function Uint256BinOpError(
              BinOpErrorCodes errorCode,
              uint256 a,
              uint256 b
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  UINT256_BINOP_ERROR_SELECTOR,
                  errorCode,
                  a,
                  b
              );
          }
          function Uint256DowncastError(
              DowncastErrorCodes errorCode,
              uint256 a
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  UINT256_DOWNCAST_ERROR_SELECTOR,
                  errorCode,
                  a
              );
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
      import "./IERC20TokenV06.sol";
      library LibERC20TokenV06 {
          bytes constant private DECIMALS_CALL_DATA = hex"313ce567";
          /// @dev Calls `IERC20TokenV06(token).approve()`.
          ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
          /// @param token The address of the token contract.
          /// @param spender The address that receives an allowance.
          /// @param allowance The allowance to set.
          function compatApprove(
              IERC20TokenV06 token,
              address spender,
              uint256 allowance
          )
              internal
          {
              bytes memory callData = abi.encodeWithSelector(
                  token.approve.selector,
                  spender,
                  allowance
              );
              _callWithOptionalBooleanResult(address(token), callData);
          }
          /// @dev Calls `IERC20TokenV06(token).approve()` and sets the allowance to the
          ///      maximum if the current approval is not already >= an amount.
          ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
          /// @param token The address of the token contract.
          /// @param spender The address that receives an allowance.
          /// @param amount The minimum allowance needed.
          function approveIfBelow(
              IERC20TokenV06 token,
              address spender,
              uint256 amount
          )
              internal
          {
              if (token.allowance(address(this), spender) < amount) {
                  compatApprove(token, spender, uint256(-1));
              }
          }
          /// @dev Calls `IERC20TokenV06(token).transfer()`.
          ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
          /// @param token The address of the token contract.
          /// @param to The address that receives the tokens
          /// @param amount Number of tokens to transfer.
          function compatTransfer(
              IERC20TokenV06 token,
              address to,
              uint256 amount
          )
              internal
          {
              bytes memory callData = abi.encodeWithSelector(
                  token.transfer.selector,
                  to,
                  amount
              );
              _callWithOptionalBooleanResult(address(token), callData);
          }
          /// @dev Calls `IERC20TokenV06(token).transferFrom()`.
          ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
          /// @param token The address of the token contract.
          /// @param from The owner of the tokens.
          /// @param to The address that receives the tokens
          /// @param amount Number of tokens to transfer.
          function compatTransferFrom(
              IERC20TokenV06 token,
              address from,
              address to,
              uint256 amount
          )
              internal
          {
              bytes memory callData = abi.encodeWithSelector(
                  token.transferFrom.selector,
                  from,
                  to,
                  amount
              );
              _callWithOptionalBooleanResult(address(token), callData);
          }
          /// @dev Retrieves the number of decimals for a token.
          ///      Returns `18` if the call reverts.
          /// @param token The address of the token contract.
          /// @return tokenDecimals The number of decimals places for the token.
          function compatDecimals(IERC20TokenV06 token)
              internal
              view
              returns (uint8 tokenDecimals)
          {
              tokenDecimals = 18;
              (bool didSucceed, bytes memory resultData) = address(token).staticcall(DECIMALS_CALL_DATA);
              if (didSucceed && resultData.length == 32) {
                  tokenDecimals = uint8(LibBytesV06.readUint256(resultData, 0));
              }
          }
          /// @dev Retrieves the allowance for a token, owner, and spender.
          ///      Returns `0` if the call reverts.
          /// @param token The address of the token contract.
          /// @param owner The owner of the tokens.
          /// @param spender The address the spender.
          /// @return allowance_ The allowance for a token, owner, and spender.
          function compatAllowance(IERC20TokenV06 token, address owner, address spender)
              internal
              view
              returns (uint256 allowance_)
          {
              (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                  abi.encodeWithSelector(
                      token.allowance.selector,
                      owner,
                      spender
                  )
              );
              if (didSucceed && resultData.length == 32) {
                  allowance_ = LibBytesV06.readUint256(resultData, 0);
              }
          }
          /// @dev Retrieves the balance for a token owner.
          ///      Returns `0` if the call reverts.
          /// @param token The address of the token contract.
          /// @param owner The owner of the tokens.
          /// @return balance The token balance of an owner.
          function compatBalanceOf(IERC20TokenV06 token, address owner)
              internal
              view
              returns (uint256 balance)
          {
              (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                  abi.encodeWithSelector(
                      token.balanceOf.selector,
                      owner
                  )
              );
              if (didSucceed && resultData.length == 32) {
                  balance = LibBytesV06.readUint256(resultData, 0);
              }
          }
          /// @dev Check if the data returned by a non-static call to an ERC20 token
          ///      is a successful result. Supported functions are `transfer()`,
          ///      `transferFrom()`, and `approve()`.
          /// @param resultData The raw data returned by a non-static call to the ERC20 token.
          /// @return isSuccessful Whether the result data indicates success.
          function isSuccessfulResult(bytes memory resultData)
              internal
              pure
              returns (bool isSuccessful)
          {
              if (resultData.length == 0) {
                  return true;
              }
              if (resultData.length == 32) {
                  uint256 result = LibBytesV06.readUint256(resultData, 0);
                  if (result == 1) {
                      return true;
                  }
              }
          }
          /// @dev Executes a call on address `target` with calldata `callData`
          ///      and asserts that either nothing was returned or a single boolean
          ///      was returned equal to `true`.
          /// @param target The call target.
          /// @param callData The abi-encoded call data.
          function _callWithOptionalBooleanResult(
              address target,
              bytes memory callData
          )
              private
          {
              (bool didSucceed, bytes memory resultData) = target.call(callData);
              if (didSucceed && isSuccessfulResult(resultData)) {
                  return;
              }
              LibRichErrorsV06.rrevert(resultData);
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "./LibStorage.sol";
      import "../external/IAllowanceTarget.sol";
      /// @dev Storage helpers for the `TokenSpender` feature.
      library LibTokenSpenderStorage {
          /// @dev Storage bucket for this feature.
          struct Storage {
              // Allowance target contract.
              IAllowanceTarget allowanceTarget;
          }
          /// @dev Get the storage bucket for this contract.
          function getStorage() internal pure returns (Storage storage stor) {
              uint256 storageSlot = LibStorage.getStorageSlot(
                  LibStorage.StorageId.TokenSpender
              );
              // Dip into assembly to change the slot pointed to by the local
              // variable `stor`.
              // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
              assembly { stor_slot := storageSlot }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
      import "../errors/LibTransformERC20RichErrors.sol";
      import "../fixins/FixinCommon.sol";
      import "../migrations/LibMigrate.sol";
      import "../external/IFlashWallet.sol";
      import "../external/FlashWallet.sol";
      import "../storage/LibTransformERC20Storage.sol";
      import "../transformers/IERC20Transformer.sol";
      import "../transformers/LibERC20Transformer.sol";
      import "./ITransformERC20.sol";
      import "./ITokenSpender.sol";
      import "./IFeature.sol";
      import "./ISimpleFunctionRegistry.sol";
      /// @dev Feature to composably transform between ERC20 tokens.
      contract TransformERC20 is
          IFeature,
          ITransformERC20,
          FixinCommon
      {
          /// @dev Stack vars for `_transformERC20Private()`.
          struct TransformERC20PrivateState {
              IFlashWallet wallet;
              address transformerDeployer;
              uint256 takerOutputTokenBalanceBefore;
              uint256 takerOutputTokenBalanceAfter;
          }
          // solhint-disable
          /// @dev Name of this feature.
          string public constant override FEATURE_NAME = "TransformERC20";
          /// @dev Version of this feature.
          uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
          /// @dev The implementation address of this feature.
          address private immutable _implementation;
          // solhint-enable
          using LibSafeMathV06 for uint256;
          using LibRichErrorsV06 for bytes;
          constructor() public {
              _implementation = address(this);
          }
          /// @dev Initialize and register this feature.
          ///      Should be delegatecalled by `Migrate.migrate()`.
          /// @param transformerDeployer The trusted deployer for transformers.
          /// @return success `LibMigrate.SUCCESS` on success.
          function migrate(address transformerDeployer) external returns (bytes4 success) {
              ISimpleFunctionRegistry(address(this))
                  .extend(this.getTransformerDeployer.selector, _implementation);
              ISimpleFunctionRegistry(address(this))
                  .extend(this.createTransformWallet.selector, _implementation);
              ISimpleFunctionRegistry(address(this))
                  .extend(this.getTransformWallet.selector, _implementation);
              ISimpleFunctionRegistry(address(this))
                  .extend(this.setTransformerDeployer.selector, _implementation);
              ISimpleFunctionRegistry(address(this))
                  .extend(this.transformERC20.selector, _implementation);
              ISimpleFunctionRegistry(address(this))
                  .extend(this._transformERC20.selector, _implementation);
              createTransformWallet();
              LibTransformERC20Storage.getStorage().transformerDeployer = transformerDeployer;
              return LibMigrate.MIGRATE_SUCCESS;
          }
          /// @dev Replace the allowed deployer for transformers.
          ///      Only callable by the owner.
          /// @param transformerDeployer The address of the trusted deployer for transformers.
          function setTransformerDeployer(address transformerDeployer)
              external
              override
              onlyOwner
          {
              LibTransformERC20Storage.getStorage().transformerDeployer = transformerDeployer;
              emit TransformerDeployerUpdated(transformerDeployer);
          }
          /// @dev Return the allowed deployer for transformers.
          /// @return deployer The transform deployer address.
          function getTransformerDeployer()
              public
              override
              view
              returns (address deployer)
          {
              return LibTransformERC20Storage.getStorage().transformerDeployer;
          }
          /// @dev Deploy a new wallet instance and replace the current one with it.
          ///      Useful if we somehow break the current wallet instance.
          ///      Anyone can call this.
          /// @return wallet The new wallet instance.
          function createTransformWallet()
              public
              override
              returns (IFlashWallet wallet)
          {
              wallet = new FlashWallet();
              LibTransformERC20Storage.getStorage().wallet = wallet;
          }
          /// @dev Executes a series of transformations to convert an ERC20 `inputToken`
          ///      to an ERC20 `outputToken`.
          /// @param inputToken The token being provided by the sender.
          ///        If `0xeee...`, ETH is implied and should be provided with the call.`
          /// @param outputToken The token to be acquired by the sender.
          ///        `0xeee...` implies ETH.
          /// @param inputTokenAmount The amount of `inputToken` to take from the sender.
          ///        If set to `uint256(-1)`, the entire spendable balance of the taker
          ///        will be solt.
          /// @param minOutputTokenAmount The minimum amount of `outputToken` the sender
          ///        must receive for the entire transformation to succeed. If set to zero,
          ///        the minimum output token transfer will not be asserted.
          /// @param transformations The transformations to execute on the token balance(s)
          ///        in sequence.
          /// @return outputTokenAmount The amount of `outputToken` received by the sender.
          function transformERC20(
              IERC20TokenV06 inputToken,
              IERC20TokenV06 outputToken,
              uint256 inputTokenAmount,
              uint256 minOutputTokenAmount,
              Transformation[] memory transformations
          )
              public
              override
              payable
              returns (uint256 outputTokenAmount)
          {
              return _transformERC20Private(
                  keccak256(msg.data),
                  msg.sender,
                  inputToken,
                  outputToken,
                  inputTokenAmount,
                  minOutputTokenAmount,
                  transformations
              );
          }
          /// @dev Internal version of `transformERC20()`. Only callable from within.
          /// @param callDataHash Hash of the ingress calldata.
          /// @param taker The taker address.
          /// @param inputToken The token being provided by the taker.
          ///        If `0xeee...`, ETH is implied and should be provided with the call.`
          /// @param outputToken The token to be acquired by the taker.
          ///        `0xeee...` implies ETH.
          /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
          ///        If set to `uint256(-1)`, the entire spendable balance of the taker
          ///        will be solt.
          /// @param minOutputTokenAmount The minimum amount of `outputToken` the taker
          ///        must receive for the entire transformation to succeed. If set to zero,
          ///        the minimum output token transfer will not be asserted.
          /// @param transformations The transformations to execute on the token balance(s)
          ///        in sequence.
          /// @return outputTokenAmount The amount of `outputToken` received by the taker.
          function _transformERC20(
              bytes32 callDataHash,
              address payable taker,
              IERC20TokenV06 inputToken,
              IERC20TokenV06 outputToken,
              uint256 inputTokenAmount,
              uint256 minOutputTokenAmount,
              Transformation[] memory transformations
          )
              public
              override
              payable
              onlySelf
              returns (uint256 outputTokenAmount)
          {
              return _transformERC20Private(
                  callDataHash,
                  taker,
                  inputToken,
                  outputToken,
                  inputTokenAmount,
                  minOutputTokenAmount,
                  transformations
              );
          }
          /// @dev Private version of `transformERC20()`.
          /// @param callDataHash Hash of the ingress calldata.
          /// @param taker The taker address.
          /// @param inputToken The token being provided by the taker.
          ///        If `0xeee...`, ETH is implied and should be provided with the call.`
          /// @param outputToken The token to be acquired by the taker.
          ///        `0xeee...` implies ETH.
          /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
          ///        If set to `uint256(-1)`, the entire spendable balance of the taker
          ///        will be solt.
          /// @param minOutputTokenAmount The minimum amount of `outputToken` the taker
          ///        must receive for the entire transformation to succeed. If set to zero,
          ///        the minimum output token transfer will not be asserted.
          /// @param transformations The transformations to execute on the token balance(s)
          ///        in sequence.
          /// @return outputTokenAmount The amount of `outputToken` received by the taker.
          function _transformERC20Private(
              bytes32 callDataHash,
              address payable taker,
              IERC20TokenV06 inputToken,
              IERC20TokenV06 outputToken,
              uint256 inputTokenAmount,
              uint256 minOutputTokenAmount,
              Transformation[] memory transformations
          )
              private
              returns (uint256 outputTokenAmount)
          {
              // If the input token amount is -1, transform the taker's entire
              // spendable balance.
              if (inputTokenAmount == uint256(-1)) {
                  inputTokenAmount = ITokenSpender(address(this))
                      .getSpendableERC20BalanceOf(inputToken, taker);
              }
              TransformERC20PrivateState memory state;
              state.wallet = getTransformWallet();
              state.transformerDeployer = getTransformerDeployer();
              // Remember the initial output token balance of the taker.
              state.takerOutputTokenBalanceBefore =
                  LibERC20Transformer.getTokenBalanceOf(outputToken, taker);
              // Pull input tokens from the taker to the wallet and transfer attached ETH.
              _transferInputTokensAndAttachedEth(
                  inputToken,
                  taker,
                  address(state.wallet),
                  inputTokenAmount
              );
              // Perform transformations.
              for (uint256 i = 0; i < transformations.length; ++i) {
                  _executeTransformation(
                      state.wallet,
                      transformations[i],
                      state.transformerDeployer,
                      taker,
                      callDataHash
                  );
              }
              // Compute how much output token has been transferred to the taker.
              state.takerOutputTokenBalanceAfter =
                  LibERC20Transformer.getTokenBalanceOf(outputToken, taker);
              if (state.takerOutputTokenBalanceAfter > state.takerOutputTokenBalanceBefore) {
                  outputTokenAmount = state.takerOutputTokenBalanceAfter.safeSub(
                      state.takerOutputTokenBalanceBefore
                  );
              } else if (state.takerOutputTokenBalanceAfter < state.takerOutputTokenBalanceBefore) {
                  LibTransformERC20RichErrors.NegativeTransformERC20OutputError(
                      address(outputToken),
                      state.takerOutputTokenBalanceBefore - state.takerOutputTokenBalanceAfter
                  ).rrevert();
              }
              // Ensure enough output token has been sent to the taker.
              if (outputTokenAmount < minOutputTokenAmount) {
                  LibTransformERC20RichErrors.IncompleteTransformERC20Error(
                      address(outputToken),
                      outputTokenAmount,
                      minOutputTokenAmount
                  ).rrevert();
              }
              // Emit an event.
              emit TransformedERC20(
                  taker,
                  address(inputToken),
                  address(outputToken),
                  inputTokenAmount,
                  outputTokenAmount
              );
          }
          /// @dev Return the current wallet instance that will serve as the execution
          ///      context for transformations.
          /// @return wallet The wallet instance.
          function getTransformWallet()
              public
              override
              view
              returns (IFlashWallet wallet)
          {
              return LibTransformERC20Storage.getStorage().wallet;
          }
          /// @dev Transfer input tokens from the taker and any attached ETH to `to`
          /// @param inputToken The token to pull from the taker.
          /// @param from The from (taker) address.
          /// @param to The recipient of tokens and ETH.
          /// @param amount Amount of `inputToken` tokens to transfer.
          function _transferInputTokensAndAttachedEth(
              IERC20TokenV06 inputToken,
              address from,
              address payable to,
              uint256 amount
          )
              private
          {
              // Transfer any attached ETH.
              if (msg.value != 0) {
                  to.transfer(msg.value);
              }
              // Transfer input tokens.
              if (!LibERC20Transformer.isTokenETH(inputToken)) {
                  // Token is not ETH, so pull ERC20 tokens.
                  ITokenSpender(address(this))._spendERC20Tokens(
                      inputToken,
                      from,
                      to,
                      amount
                  );
              } else if (msg.value < amount) {
                   // Token is ETH, so the caller must attach enough ETH to the call.
                  LibTransformERC20RichErrors.InsufficientEthAttachedError(
                      msg.value,
                      amount
                  ).rrevert();
              }
          }
          /// @dev Executs a transformer in the context of `wallet`.
          /// @param wallet The wallet instance.
          /// @param transformation The transformation.
          /// @param transformerDeployer The address of the transformer deployer.
          /// @param taker The taker address.
          /// @param callDataHash Hash of the calldata.
          function _executeTransformation(
              IFlashWallet wallet,
              Transformation memory transformation,
              address transformerDeployer,
              address payable taker,
              bytes32 callDataHash
          )
              private
          {
              // Derive the transformer address from the deployment nonce.
              address payable transformer = LibERC20Transformer.getDeployedAddress(
                  transformerDeployer,
                  transformation.deploymentNonce
              );
              // Call `transformer.transform()` as the wallet.
              bytes memory resultData = wallet.executeDelegateCall(
                  // The call target.
                  transformer,
                  // Call data.
                  abi.encodeWithSelector(
                      IERC20Transformer.transform.selector,
                      callDataHash,
                      taker,
                      transformation.data
                  )
              );
              // Ensure the transformer returned the magic bytes.
              if (resultData.length != 32 ||
                  abi.decode(resultData, (bytes4)) != LibERC20Transformer.TRANSFORMER_SUCCESS
              ) {
                  LibTransformERC20RichErrors.TransformerFailedError(
                      transformer,
                      transformation.data,
                      resultData
                  ).rrevert();
              }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "./LibStorage.sol";
      import "../external/IFlashWallet.sol";
      /// @dev Storage helpers for the `TokenSpender` feature.
      library LibTransformERC20Storage {
          /// @dev Storage bucket for this feature.
          struct Storage {
              // The current wallet instance.
              IFlashWallet wallet;
              // The transformer deployer address.
              address transformerDeployer;
          }
          /// @dev Get the storage bucket for this contract.
          function getStorage() internal pure returns (Storage storage stor) {
              uint256 storageSlot = LibStorage.getStorageSlot(
                  LibStorage.StorageId.TransformERC20
              );
              // Dip into assembly to change the slot pointed to by the local
              // variable `stor`.
              // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
              assembly { stor_slot := storageSlot }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
      library LibERC20Transformer {
          using LibERC20TokenV06 for IERC20TokenV06;
          /// @dev ETH pseudo-token address.
          address constant internal ETH_TOKEN_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
          /// @dev Return value indicating success in `IERC20Transformer.transform()`.
          ///      This is just `keccak256('TRANSFORMER_SUCCESS')`.
          bytes4 constant internal TRANSFORMER_SUCCESS = 0x13c9929e;
          /// @dev Transfer ERC20 tokens and ETH.
          /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
          /// @param to The recipient.
          /// @param amount The transfer amount.
          function transformerTransfer(
              IERC20TokenV06 token,
              address payable to,
              uint256 amount
          )
              internal
          {
              if (isTokenETH(token)) {
                  to.transfer(amount);
              } else {
                  token.compatTransfer(to, amount);
              }
          }
          /// @dev Check if a token is the ETH pseudo-token.
          /// @param token The token to check.
          /// @return isETH `true` if the token is the ETH pseudo-token.
          function isTokenETH(IERC20TokenV06 token)
              internal
              pure
              returns (bool isETH)
          {
              return address(token) == ETH_TOKEN_ADDRESS;
          }
          /// @dev Check the balance of an ERC20 token or ETH.
          /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
          /// @param owner Holder of the tokens.
          /// @return tokenBalance The balance of `owner`.
          function getTokenBalanceOf(IERC20TokenV06 token, address owner)
              internal
              view
              returns (uint256 tokenBalance)
          {
              if (isTokenETH(token)) {
                  return owner.balance;
              }
              return token.balanceOf(owner);
          }
          /// @dev RLP-encode a 32-bit or less account nonce.
          /// @param nonce A positive integer in the range 0 <= nonce < 2^32.
          /// @return rlpNonce The RLP encoding.
          function rlpEncodeNonce(uint32 nonce)
              internal
              pure
              returns (bytes memory rlpNonce)
          {
              // See https://github.com/ethereum/wiki/wiki/RLP for RLP encoding rules.
              if (nonce == 0) {
                  rlpNonce = new bytes(1);
                  rlpNonce[0] = 0x80;
              } else if (nonce < 0x80) {
                  rlpNonce = new bytes(1);
                  rlpNonce[0] = byte(uint8(nonce));
              } else if (nonce <= 0xFF) {
                  rlpNonce = new bytes(2);
                  rlpNonce[0] = 0x81;
                  rlpNonce[1] = byte(uint8(nonce));
              } else if (nonce <= 0xFFFF) {
                  rlpNonce = new bytes(3);
                  rlpNonce[0] = 0x82;
                  rlpNonce[1] = byte(uint8((nonce & 0xFF00) >> 8));
                  rlpNonce[2] = byte(uint8(nonce));
              } else if (nonce <= 0xFFFFFF) {
                  rlpNonce = new bytes(4);
                  rlpNonce[0] = 0x83;
                  rlpNonce[1] = byte(uint8((nonce & 0xFF0000) >> 16));
                  rlpNonce[2] = byte(uint8((nonce & 0xFF00) >> 8));
                  rlpNonce[3] = byte(uint8(nonce));
              } else {
                  rlpNonce = new bytes(5);
                  rlpNonce[0] = 0x84;
                  rlpNonce[1] = byte(uint8((nonce & 0xFF000000) >> 24));
                  rlpNonce[2] = byte(uint8((nonce & 0xFF0000) >> 16));
                  rlpNonce[3] = byte(uint8((nonce & 0xFF00) >> 8));
                  rlpNonce[4] = byte(uint8(nonce));
              }
          }
          /// @dev Compute the expected deployment address by `deployer` at
          ///      the nonce given by `deploymentNonce`.
          /// @param deployer The address of the deployer.
          /// @param deploymentNonce The nonce that the deployer had when deploying
          ///        a contract.
          /// @return deploymentAddress The deployment address.
          function getDeployedAddress(address deployer, uint32 deploymentNonce)
              internal
              pure
              returns (address payable deploymentAddress)
          {
              // The address of if a deployed contract is the lower 20 bytes of the
              // hash of the RLP-encoded deployer's account address + account nonce.
              // See: https://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
              bytes memory rlpNonce = rlpEncodeNonce(deploymentNonce);
              return address(uint160(uint256(keccak256(abi.encodePacked(
                  byte(uint8(0xC0 + 21 + rlpNonce.length)),
                  byte(uint8(0x80 + 20)),
                  deployer,
                  rlpNonce
              )))));
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../ZeroEx.sol";
      import "../features/IOwnable.sol";
      import "../features/TokenSpender.sol";
      import "../features/TransformERC20.sol";
      import "../external/AllowanceTarget.sol";
      import "./InitialMigration.sol";
      /// @dev A contract for deploying and configuring the full ZeroEx contract.
      contract FullMigration {
          // solhint-disable no-empty-blocks,indent
          /// @dev Features to add the the proxy contract.
          struct Features {
              SimpleFunctionRegistry registry;
              Ownable ownable;
              TokenSpender tokenSpender;
              TransformERC20 transformERC20;
          }
          /// @dev Parameters needed to initialize features.
          struct MigrateOpts {
              address transformerDeployer;
          }
          /// @dev The allowed caller of `deploy()`.
          address public immutable deployer;
          /// @dev The initial migration contract.
          InitialMigration private _initialMigration;
          /// @dev Instantiate this contract and set the allowed caller of `deploy()`
          ///      to `deployer`.
          /// @param deployer_ The allowed caller of `deploy()`.
          constructor(address payable deployer_)
              public
          {
              deployer = deployer_;
              // Create an initial migration contract with this contract set to the
              // allowed deployer.
              _initialMigration = new InitialMigration(address(this));
          }
          /// @dev Deploy the `ZeroEx` contract with the full feature set,
          ///      transfer ownership to `owner`, then self-destruct.
          /// @param owner The owner of the contract.
          /// @param features Features to add to the proxy.
          /// @return zeroEx The deployed and configured `ZeroEx` contract.
          /// @param migrateOpts Parameters needed to initialize features.
          function deploy(
              address payable owner,
              Features memory features,
              MigrateOpts memory migrateOpts
          )
              public
              returns (ZeroEx zeroEx)
          {
              require(msg.sender == deployer, "FullMigration/INVALID_SENDER");
              // Perform the initial migration with the owner set to this contract.
              zeroEx = _initialMigration.deploy(
                  address(uint160(address(this))),
                  InitialMigration.BootstrapFeatures({
                      registry: features.registry,
                      ownable: features.ownable
                  })
              );
              // Add features.
              _addFeatures(zeroEx, owner, features, migrateOpts);
              // Transfer ownership to the real owner.
              IOwnable(address(zeroEx)).transferOwnership(owner);
              // Self-destruct.
              this.die(owner);
          }
          /// @dev Destroy this contract. Only callable from ourselves (from `deploy()`).
          /// @param ethRecipient Receiver of any ETH in this contract.
          function die(address payable ethRecipient)
              external
              virtual
          {
              require(msg.sender == address(this), "FullMigration/INVALID_SENDER");
              // This contract should not hold any funds but we send
              // them to the ethRecipient just in case.
              selfdestruct(ethRecipient);
          }
          /// @dev Deploy and register features to the ZeroEx contract.
          /// @param zeroEx The bootstrapped ZeroEx contract.
          /// @param owner The ultimate owner of the ZeroEx contract.
          /// @param features Features to add to the proxy.
          /// @param migrateOpts Parameters needed to initialize features.
          function _addFeatures(
              ZeroEx zeroEx,
              address owner,
              Features memory features,
              MigrateOpts memory migrateOpts
          )
              private
          {
              IOwnable ownable = IOwnable(address(zeroEx));
              // TokenSpender
              {
                  // Create the allowance target.
                  AllowanceTarget allowanceTarget = new AllowanceTarget();
                  // Let the ZeroEx contract use the allowance target.
                  allowanceTarget.addAuthorizedAddress(address(zeroEx));
                  // Transfer ownership of the allowance target to the (real) owner.
                  allowanceTarget.transferOwnership(owner);
                  // Register the feature.
                  ownable.migrate(
                      address(features.tokenSpender),
                      abi.encodeWithSelector(
                          TokenSpender.migrate.selector,
                          allowanceTarget
                      ),
                      address(this)
                  );
              }
              // TransformERC20
              {
                  // Register the feature.
                  ownable.migrate(
                      address(features.transformERC20),
                      abi.encodeWithSelector(
                          TransformERC20.migrate.selector,
                          migrateOpts.transformerDeployer
                      ),
                      address(this)
                  );
              }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../ZeroEx.sol";
      import "../features/IBootstrap.sol";
      import "../features/SimpleFunctionRegistry.sol";
      import "../features/Ownable.sol";
      import "./LibBootstrap.sol";
      /// @dev A contract for deploying and configuring a minimal ZeroEx contract.
      contract InitialMigration {
          /// @dev Features to bootstrap into the the proxy contract.
          struct BootstrapFeatures {
              SimpleFunctionRegistry registry;
              Ownable ownable;
          }
          /// @dev The allowed caller of `deploy()`. In production, this would be
          ///      the governor.
          address public immutable deployer;
          /// @dev The real address of this contract.
          address private immutable _implementation;
          /// @dev Instantiate this contract and set the allowed caller of `deploy()`
          ///      to `deployer_`.
          /// @param deployer_ The allowed caller of `deploy()`.
          constructor(address deployer_) public {
              deployer = deployer_;
              _implementation = address(this);
          }
          /// @dev Deploy the `ZeroEx` contract with the minimum feature set,
          ///      transfers ownership to `owner`, then self-destructs.
          ///      Only callable by `deployer` set in the contstructor.
          /// @param owner The owner of the contract.
          /// @param features Features to bootstrap into the proxy.
          /// @return zeroEx The deployed and configured `ZeroEx` contract.
          function deploy(address payable owner, BootstrapFeatures memory features)
              public
              virtual
              returns (ZeroEx zeroEx)
          {
              // Must be called by the allowed deployer.
              require(msg.sender == deployer, "InitialMigration/INVALID_SENDER");
              // Deploy the ZeroEx contract, setting ourselves as the bootstrapper.
              zeroEx = new ZeroEx();
              // Bootstrap the initial feature set.
              IBootstrap(address(zeroEx)).bootstrap(
                  address(this),
                  abi.encodeWithSelector(this.bootstrap.selector, owner, features)
              );
              // Self-destruct. This contract should not hold any funds but we send
              // them to the owner just in case.
              this.die(owner);
          }
          /// @dev Sets up the initial state of the `ZeroEx` contract.
          ///      The `ZeroEx` contract will delegatecall into this function.
          /// @param owner The new owner of the ZeroEx contract.
          /// @param features Features to bootstrap into the proxy.
          /// @return success Magic bytes if successful.
          function bootstrap(address owner, BootstrapFeatures memory features)
              public
              virtual
              returns (bytes4 success)
          {
              // Deploy and migrate the initial features.
              // Order matters here.
              // Initialize Registry.
              LibBootstrap.delegatecallBootstrapFunction(
                  address(features.registry),
                  abi.encodeWithSelector(
                      SimpleFunctionRegistry.bootstrap.selector
                  )
              );
              // Initialize Ownable.
              LibBootstrap.delegatecallBootstrapFunction(
                  address(features.ownable),
                  abi.encodeWithSelector(
                      Ownable.bootstrap.selector
                  )
              );
              // De-register `SimpleFunctionRegistry._extendSelf`.
              SimpleFunctionRegistry(address(this)).rollback(
                  SimpleFunctionRegistry._extendSelf.selector,
                  address(0)
              );
              // Transfer ownership to the real owner.
              Ownable(address(this)).transferOwnership(owner);
              success = LibBootstrap.BOOTSTRAP_SUCCESS;
          }
          /// @dev Self-destructs this contract. Only callable by this contract.
          /// @param ethRecipient Who to transfer outstanding ETH to.
          function die(address payable ethRecipient) public virtual {
              require(msg.sender == _implementation, "InitialMigration/INVALID_SENDER");
              selfdestruct(ethRecipient);
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
      import "../errors/LibTransformERC20RichErrors.sol";
      import "./Transformer.sol";
      import "./LibERC20Transformer.sol";
      /// @dev A transformer that transfers tokens to arbitrary addresses.
      contract AffiliateFeeTransformer is
          Transformer
      {
          // solhint-disable no-empty-blocks
          using LibRichErrorsV06 for bytes;
          using LibSafeMathV06 for uint256;
          using LibERC20Transformer for IERC20TokenV06;
          /// @dev Information for a single fee.
          struct TokenFee {
              // The token to transfer to `recipient`.
              IERC20TokenV06 token;
              // Amount of each `token` to transfer to `recipient`.
              // If `amount == uint256(-1)`, the entire balance of `token` will be
              // transferred.
              uint256 amount;
              // Recipient of `token`.
              address payable recipient;
          }
          uint256 private constant MAX_UINT256 = uint256(-1);
          /// @dev Create this contract.
          constructor()
              public
              Transformer()
          {}
          /// @dev Transfers tokens to recipients.
          /// @param data ABI-encoded `TokenFee[]`, indicating which tokens to transfer.
          /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
          function transform(
              bytes32, // callDataHash,
              address payable, // taker,
              bytes calldata data
          )
              external
              override
              returns (bytes4 success)
          {
              TokenFee[] memory fees = abi.decode(data, (TokenFee[]));
              // Transfer tokens to recipients.
              for (uint256 i = 0; i < fees.length; ++i) {
                  uint256 amount = fees[i].amount;
                  if (amount == MAX_UINT256) {
                      amount = LibERC20Transformer.getTokenBalanceOf(fees[i].token, address(this));
                  }
                  if (amount != 0) {
                      fees[i].token.transformerTransfer(fees[i].recipient, amount);
                  }
              }
              return LibERC20Transformer.TRANSFORMER_SUCCESS;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "../errors/LibTransformERC20RichErrors.sol";
      import "./IERC20Transformer.sol";
      /// @dev Abstract base class for transformers.
      abstract contract Transformer is
          IERC20Transformer
      {
          using LibRichErrorsV06 for bytes;
          /// @dev The address of the deployer.
          address public immutable deployer;
          /// @dev The original address of this contract.
          address private immutable _implementation;
          /// @dev Create this contract.
          constructor() public {
              deployer = msg.sender;
              _implementation = address(this);
          }
          /// @dev Destruct this contract. Only callable by the deployer and will not
          ///      succeed in the context of a delegatecall (from another contract).
          /// @param ethRecipient The recipient of ETH held in this contract.
          function die(address payable ethRecipient)
              external
              virtual
          {
              // Only the deployer can call this.
              if (msg.sender != deployer) {
                  LibTransformERC20RichErrors
                      .OnlyCallableByDeployerError(msg.sender, deployer)
                      .rrevert();
              }
              // Must be executing our own context.
              if (address(this) != _implementation) {
                  LibTransformERC20RichErrors
                      .InvalidExecutionContextError(address(this), _implementation)
                      .rrevert();
              }
              selfdestruct(ethRecipient);
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibMathV06.sol";
      import "../errors/LibTransformERC20RichErrors.sol";
      import "../vendor/v3/IExchange.sol";
      import "./Transformer.sol";
      import "./LibERC20Transformer.sol";
      /// @dev A transformer that fills an ERC20 market sell/buy quote.
      contract FillQuoteTransformer is
          Transformer
      {
          using LibERC20TokenV06 for IERC20TokenV06;
          using LibERC20Transformer for IERC20TokenV06;
          using LibSafeMathV06 for uint256;
          using LibRichErrorsV06 for bytes;
          /// @dev Whether we are performing a market sell or buy.
          enum Side {
              Sell,
              Buy
          }
          /// @dev Transform data to ABI-encode and pass into `transform()`.
          struct TransformData {
              // Whether we aer performing a market sell or buy.
              Side side;
              // The token being sold.
              // This should be an actual token, not the ETH pseudo-token.
              IERC20TokenV06 sellToken;
              // The token being bought.
              // This should be an actual token, not the ETH pseudo-token.
              IERC20TokenV06 buyToken;
              // The orders to fill.
              IExchange.Order[] orders;
              // Signatures for each respective order in `orders`.
              bytes[] signatures;
              // Maximum fill amount for each order. This may be shorter than the
              // number of orders, where missing entries will be treated as `uint256(-1)`.
              // For sells, this will be the maximum sell amount (taker asset).
              // For buys, this will be the maximum buy amount (maker asset).
              uint256[] maxOrderFillAmounts;
              // Amount of `sellToken` to sell or `buyToken` to buy.
              // For sells, this may be `uint256(-1)` to sell the entire balance of
              // `sellToken`.
              uint256 fillAmount;
          }
          /// @dev Results of a call to `_fillOrder()`.
          struct FillOrderResults {
              // The amount of taker tokens sold, according to balance checks.
              uint256 takerTokenSoldAmount;
              // The amount of maker tokens sold, according to balance checks.
              uint256 makerTokenBoughtAmount;
              // The amount of protocol fee paid.
              uint256 protocolFeePaid;
          }
          /// @dev The Exchange ERC20Proxy ID.
          bytes4 private constant ERC20_ASSET_PROXY_ID = 0xf47261b0;
          /// @dev Maximum uint256 value.
          uint256 private constant MAX_UINT256 = uint256(-1);
          /// @dev The Exchange contract.
          IExchange public immutable exchange;
          /// @dev The ERC20Proxy address.
          address public immutable erc20Proxy;
          /// @dev Create this contract.
          /// @param exchange_ The Exchange V3 instance.
          constructor(IExchange exchange_)
              public
              Transformer()
          {
              exchange = exchange_;
              erc20Proxy = exchange_.getAssetProxy(ERC20_ASSET_PROXY_ID);
          }
          /// @dev Sell this contract's entire balance of of `sellToken` in exchange
          ///      for `buyToken` by filling `orders`. Protocol fees should be attached
          ///      to this call. `buyToken` and excess ETH will be transferred back to the caller.
          /// @param data_ ABI-encoded `TransformData`.
          /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
          function transform(
              bytes32, // callDataHash,
              address payable, // taker,
              bytes calldata data_
          )
              external
              override
              returns (bytes4 success)
          {
              TransformData memory data = abi.decode(data_, (TransformData));
              // Validate data fields.
              if (data.sellToken.isTokenETH() || data.buyToken.isTokenETH()) {
                  LibTransformERC20RichErrors.InvalidTransformDataError(
                      LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_TOKENS,
                      data_
                  ).rrevert();
              }
              if (data.orders.length != data.signatures.length) {
                  LibTransformERC20RichErrors.InvalidTransformDataError(
                      LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_ARRAY_LENGTH,
                      data_
                  ).rrevert();
              }
              if (data.side == Side.Sell && data.fillAmount == MAX_UINT256) {
                  // If `sellAmount == -1 then we are selling
                  // the entire balance of `sellToken`. This is useful in cases where
                  // the exact sell amount is not exactly known in advance, like when
                  // unwrapping Chai/cUSDC/cDAI.
                  data.fillAmount = data.sellToken.getTokenBalanceOf(address(this));
              }
              // Approve the ERC20 proxy to spend `sellToken`.
              data.sellToken.approveIfBelow(erc20Proxy, data.fillAmount);
              // Fill the orders.
              uint256 singleProtocolFee = exchange.protocolFeeMultiplier().safeMul(tx.gasprice);
              uint256 ethRemaining = address(this).balance;
              uint256 boughtAmount = 0;
              uint256 soldAmount = 0;
              for (uint256 i = 0; i < data.orders.length; ++i) {
                  // Check if we've hit our targets.
                  if (data.side == Side.Sell) {
                      // Market sell check.
                      if (soldAmount >= data.fillAmount) {
                          break;
                      }
                  } else {
                      // Market buy check.
                      if (boughtAmount >= data.fillAmount) {
                          break;
                      }
                  }
                  // Ensure we have enough ETH to cover the protocol fee.
                  if (ethRemaining < singleProtocolFee) {
                      LibTransformERC20RichErrors
                          .InsufficientProtocolFeeError(ethRemaining, singleProtocolFee)
                          .rrevert();
                  }
                  // Fill the order.
                  FillOrderResults memory results;
                  if (data.side == Side.Sell) {
                      // Market sell.
                      results = _sellToOrder(
                          data.buyToken,
                          data.sellToken,
                          data.orders[i],
                          data.signatures[i],
                          data.fillAmount.safeSub(soldAmount).min256(
                              data.maxOrderFillAmounts.length > i
                              ? data.maxOrderFillAmounts[i]
                              : MAX_UINT256
                          ),
                          singleProtocolFee
                      );
                  } else {
                      // Market buy.
                      results = _buyFromOrder(
                          data.buyToken,
                          data.sellToken,
                          data.orders[i],
                          data.signatures[i],
                          data.fillAmount.safeSub(boughtAmount).min256(
                              data.maxOrderFillAmounts.length > i
                              ? data.maxOrderFillAmounts[i]
                              : MAX_UINT256
                          ),
                          singleProtocolFee
                      );
                  }
                  // Accumulate totals.
                  soldAmount = soldAmount.safeAdd(results.takerTokenSoldAmount);
                  boughtAmount = boughtAmount.safeAdd(results.makerTokenBoughtAmount);
                  ethRemaining = ethRemaining.safeSub(results.protocolFeePaid);
              }
              // Ensure we hit our targets.
              if (data.side == Side.Sell) {
                  // Market sell check.
                  if (soldAmount < data.fillAmount) {
                      LibTransformERC20RichErrors
                          .IncompleteFillSellQuoteError(
                              address(data.sellToken),
                              soldAmount,
                              data.fillAmount
                          ).rrevert();
                  }
              } else {
                  // Market buy check.
                  if (boughtAmount < data.fillAmount) {
                      LibTransformERC20RichErrors
                          .IncompleteFillBuyQuoteError(
                              address(data.buyToken),
                              boughtAmount,
                              data.fillAmount
                          ).rrevert();
                  }
              }
              return LibERC20Transformer.TRANSFORMER_SUCCESS;
          }
          /// @dev Try to sell up to `sellAmount` from an order.
          /// @param makerToken The maker/buy token.
          /// @param takerToken The taker/sell token.
          /// @param order The order to fill.
          /// @param signature The signature for `order`.
          /// @param sellAmount Amount of taker token to sell.
          /// @param protocolFee The protocol fee needed to fill `order`.
          function _sellToOrder(
              IERC20TokenV06 makerToken,
              IERC20TokenV06 takerToken,
              IExchange.Order memory order,
              bytes memory signature,
              uint256 sellAmount,
              uint256 protocolFee
          )
              private
              returns (FillOrderResults memory results)
          {
              IERC20TokenV06 takerFeeToken =
                  _getTokenFromERC20AssetData(order.takerFeeAssetData);
              uint256 takerTokenFillAmount = sellAmount;
              if (order.takerFee != 0) {
                  if (takerFeeToken == makerToken) {
                      // Taker fee is payable in the maker token, so we need to
                      // approve the proxy to spend the maker token.
                      // It isn't worth computing the actual taker fee
                      // since `approveIfBelow()` will set the allowance to infinite. We
                      // just need a reasonable upper bound to avoid unnecessarily re-approving.
                      takerFeeToken.approveIfBelow(erc20Proxy, order.takerFee);
                  } else if (takerFeeToken == takerToken){
                      // Taker fee is payable in the taker token, so we need to
                      // reduce the fill amount to cover the fee.
                      // takerTokenFillAmount' =
                      //   (takerTokenFillAmount * order.takerAssetAmount) /
                      //   (order.takerAssetAmount + order.takerFee)
                      takerTokenFillAmount = LibMathV06.getPartialAmountCeil(
                          order.takerAssetAmount,
                          order.takerAssetAmount.safeAdd(order.takerFee),
                          sellAmount
                      );
                  } else {
                      //  Only support taker or maker asset denominated taker fees.
                      LibTransformERC20RichErrors.InvalidTakerFeeTokenError(
                          address(takerFeeToken)
                      ).rrevert();
                  }
              }
              // Clamp fill amount to order size.
              takerTokenFillAmount = LibSafeMathV06.min256(
                  takerTokenFillAmount,
                  order.takerAssetAmount
              );
              // Perform the fill.
              return _fillOrder(
                  order,
                  signature,
                  takerTokenFillAmount,
                  protocolFee,
                  makerToken,
                  takerFeeToken == takerToken
              );
          }
          /// @dev Try to buy up to `buyAmount` from an order.
          /// @param makerToken The maker/buy token.
          /// @param takerToken The taker/sell token.
          /// @param order The order to fill.
          /// @param signature The signature for `order`.
          /// @param buyAmount Amount of maker token to buy.
          /// @param protocolFee The protocol fee needed to fill `order`.
          function _buyFromOrder(
              IERC20TokenV06 makerToken,
              IERC20TokenV06 takerToken,
              IExchange.Order memory order,
              bytes memory signature,
              uint256 buyAmount,
              uint256 protocolFee
          )
              private
              returns (FillOrderResults memory results)
          {
              IERC20TokenV06 takerFeeToken =
                  _getTokenFromERC20AssetData(order.takerFeeAssetData);
              // Compute the default taker token fill amount.
              uint256 takerTokenFillAmount = LibMathV06.getPartialAmountCeil(
                  buyAmount,
                  order.makerAssetAmount,
                  order.takerAssetAmount
              );
              if (order.takerFee != 0) {
                  if (takerFeeToken == makerToken) {
                      // Taker fee is payable in the maker token.
                      // Adjust the taker token fill amount to account for maker
                      // tokens being lost to the taker fee.
                      // takerTokenFillAmount' =
                      //  (order.takerAssetAmount * buyAmount) /
                      //  (order.makerAssetAmount - order.takerFee)
                      takerTokenFillAmount = LibMathV06.getPartialAmountCeil(
                          buyAmount,
                          order.makerAssetAmount.safeSub(order.takerFee),
                          order.takerAssetAmount
                      );
                      // Approve the proxy to spend the maker token.
                      // It isn't worth computing the actual taker fee
                      // since `approveIfBelow()` will set the allowance to infinite. We
                      // just need a reasonable upper bound to avoid unnecessarily re-approving.
                      takerFeeToken.approveIfBelow(erc20Proxy, order.takerFee);
                  } else if (takerFeeToken != takerToken) {
                      //  Only support taker or maker asset denominated taker fees.
                      LibTransformERC20RichErrors.InvalidTakerFeeTokenError(
                          address(takerFeeToken)
                      ).rrevert();
                  }
              }
              // Clamp to order size.
              takerTokenFillAmount = LibSafeMathV06.min256(
                  order.takerAssetAmount,
                  takerTokenFillAmount
              );
              // Perform the fill.
              return _fillOrder(
                  order,
                  signature,
                  takerTokenFillAmount,
                  protocolFee,
                  makerToken,
                  takerFeeToken == takerToken
              );
          }
          /// @dev Attempt to fill an order. If the fill reverts, the revert will be
          ///      swallowed and `results` will be zeroed out.
          /// @param order The order to fill.
          /// @param signature The order signature.
          /// @param takerAssetFillAmount How much taker asset to fill.
          /// @param protocolFee The protocol fee needed to fill this order.
          /// @param makerToken The maker token.
          /// @param isTakerFeeInTakerToken Whether the taker fee token is the same as the
          ///        taker token.
          function _fillOrder(
              IExchange.Order memory order,
              bytes memory signature,
              uint256 takerAssetFillAmount,
              uint256 protocolFee,
              IERC20TokenV06 makerToken,
              bool isTakerFeeInTakerToken
          )
              private
              returns (FillOrderResults memory results)
          {
              // Track changes in the maker token balance.
              uint256 initialMakerTokenBalance = makerToken.balanceOf(address(this));
              try
                  exchange.fillOrder
                      {value: protocolFee}
                      (order, takerAssetFillAmount, signature)
                  returns (IExchange.FillResults memory fillResults)
              {
                  // Update maker quantity based on changes in token balances.
                  results.makerTokenBoughtAmount = makerToken.balanceOf(address(this))
                      .safeSub(initialMakerTokenBalance);
                  // We can trust the other fill result quantities.
                  results.protocolFeePaid = fillResults.protocolFeePaid;
                  results.takerTokenSoldAmount = fillResults.takerAssetFilledAmount;
                  // If the taker fee is payable in the taker asset, include the
                  // taker fee in the total amount sold.
                  if (isTakerFeeInTakerToken) {
                      results.takerTokenSoldAmount =
                          results.takerTokenSoldAmount.safeAdd(fillResults.takerFeePaid);
                  }
              } catch (bytes memory) {
                  // Swallow failures, leaving all results as zero.
              }
          }
          /// @dev Extract the token from plain ERC20 asset data.
          ///      If the asset-data is empty, a zero token address will be returned.
          /// @param assetData The order asset data.
          function _getTokenFromERC20AssetData(bytes memory assetData)
              private
              pure
              returns (IERC20TokenV06 token)
          {
              if (assetData.length == 0) {
                  return IERC20TokenV06(address(0));
              }
              if (assetData.length != 36 ||
                  LibBytesV06.readBytes4(assetData, 0) != ERC20_ASSET_PROXY_ID)
              {
                  LibTransformERC20RichErrors
                      .InvalidERC20AssetDataError(assetData)
                      .rrevert();
              }
              return IERC20TokenV06(LibBytesV06.readAddress(assetData, 16));
          }
      }
      /*
        Copyright 2019 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      import "./LibSafeMathV06.sol";
      import "./errors/LibRichErrorsV06.sol";
      import "./errors/LibMathRichErrorsV06.sol";
      library LibMathV06 {
          using LibSafeMathV06 for uint256;
          /// @dev Calculates partial value given a numerator and denominator rounded down.
          ///      Reverts if rounding error is >= 0.1%
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to calculate partial of.
          /// @return partialAmount Partial value of target rounded down.
          function safeGetPartialAmountFloor(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (uint256 partialAmount)
          {
              if (isRoundingErrorFloor(
                      numerator,
                      denominator,
                      target
              )) {
                  LibRichErrorsV06.rrevert(LibMathRichErrorsV06.RoundingError(
                      numerator,
                      denominator,
                      target
                  ));
              }
              partialAmount = numerator.safeMul(target).safeDiv(denominator);
              return partialAmount;
          }
          /// @dev Calculates partial value given a numerator and denominator rounded down.
          ///      Reverts if rounding error is >= 0.1%
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to calculate partial of.
          /// @return partialAmount Partial value of target rounded up.
          function safeGetPartialAmountCeil(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (uint256 partialAmount)
          {
              if (isRoundingErrorCeil(
                      numerator,
                      denominator,
                      target
              )) {
                  LibRichErrorsV06.rrevert(LibMathRichErrorsV06.RoundingError(
                      numerator,
                      denominator,
                      target
                  ));
              }
              // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
              //       ceil(a / b) = floor((a + b - 1) / b)
              // To implement `ceil(a / b)` using safeDiv.
              partialAmount = numerator.safeMul(target)
                  .safeAdd(denominator.safeSub(1))
                  .safeDiv(denominator);
              return partialAmount;
          }
          /// @dev Calculates partial value given a numerator and denominator rounded down.
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to calculate partial of.
          /// @return partialAmount Partial value of target rounded down.
          function getPartialAmountFloor(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (uint256 partialAmount)
          {
              partialAmount = numerator.safeMul(target).safeDiv(denominator);
              return partialAmount;
          }
          /// @dev Calculates partial value given a numerator and denominator rounded down.
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to calculate partial of.
          /// @return partialAmount Partial value of target rounded up.
          function getPartialAmountCeil(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (uint256 partialAmount)
          {
              // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
              //       ceil(a / b) = floor((a + b - 1) / b)
              // To implement `ceil(a / b)` using safeDiv.
              partialAmount = numerator.safeMul(target)
                  .safeAdd(denominator.safeSub(1))
                  .safeDiv(denominator);
              return partialAmount;
          }
          /// @dev Checks if rounding error >= 0.1% when rounding down.
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to multiply with numerator/denominator.
          /// @return isError Rounding error is present.
          function isRoundingErrorFloor(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (bool isError)
          {
              if (denominator == 0) {
                  LibRichErrorsV06.rrevert(LibMathRichErrorsV06.DivisionByZeroError());
              }
              // The absolute rounding error is the difference between the rounded
              // value and the ideal value. The relative rounding error is the
              // absolute rounding error divided by the absolute value of the
              // ideal value. This is undefined when the ideal value is zero.
              //
              // The ideal value is `numerator * target / denominator`.
              // Let's call `numerator * target % denominator` the remainder.
              // The absolute error is `remainder / denominator`.
              //
              // When the ideal value is zero, we require the absolute error to
              // be zero. Fortunately, this is always the case. The ideal value is
              // zero iff `numerator == 0` and/or `target == 0`. In this case the
              // remainder and absolute error are also zero.
              if (target == 0 || numerator == 0) {
                  return false;
              }
              // Otherwise, we want the relative rounding error to be strictly
              // less than 0.1%.
              // The relative error is `remainder / (numerator * target)`.
              // We want the relative error less than 1 / 1000:
              //        remainder / (numerator * denominator)  <  1 / 1000
              // or equivalently:
              //        1000 * remainder  <  numerator * target
              // so we have a rounding error iff:
              //        1000 * remainder  >=  numerator * target
              uint256 remainder = mulmod(
                  target,
                  numerator,
                  denominator
              );
              isError = remainder.safeMul(1000) >= numerator.safeMul(target);
              return isError;
          }
          /// @dev Checks if rounding error >= 0.1% when rounding up.
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to multiply with numerator/denominator.
          /// @return isError Rounding error is present.
          function isRoundingErrorCeil(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (bool isError)
          {
              if (denominator == 0) {
                  LibRichErrorsV06.rrevert(LibMathRichErrorsV06.DivisionByZeroError());
              }
              // See the comments in `isRoundingError`.
              if (target == 0 || numerator == 0) {
                  // When either is zero, the ideal value and rounded value are zero
                  // and there is no rounding error. (Although the relative error
                  // is undefined.)
                  return false;
              }
              // Compute remainder as before
              uint256 remainder = mulmod(
                  target,
                  numerator,
                  denominator
              );
              remainder = denominator.safeSub(remainder) % denominator;
              isError = remainder.safeMul(1000) >= numerator.safeMul(target);
              return isError;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibMathRichErrorsV06 {
          // bytes4(keccak256("DivisionByZeroError()"))
          bytes internal constant DIVISION_BY_ZERO_ERROR =
              hex"a791837c";
          // bytes4(keccak256("RoundingError(uint256,uint256,uint256)"))
          bytes4 internal constant ROUNDING_ERROR_SELECTOR =
              0x339f3de2;
          // solhint-disable func-name-mixedcase
          function DivisionByZeroError()
              internal
              pure
              returns (bytes memory)
          {
              return DIVISION_BY_ZERO_ERROR;
          }
          function RoundingError(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  ROUNDING_ERROR_SELECTOR,
                  numerator,
                  denominator,
                  target
              );
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      /// @dev Interface to the V3 Exchange.
      interface IExchange {
          /// @dev V3 Order structure.
          struct Order {
              // Address that created the order.
              address makerAddress;
              // Address that is allowed to fill the order.
              // If set to 0, any address is allowed to fill the order.
              address takerAddress;
              // Address that will recieve fees when order is filled.
              address feeRecipientAddress;
              // Address that is allowed to call Exchange contract methods that affect this order.
              // If set to 0, any address is allowed to call these methods.
              address senderAddress;
              // Amount of makerAsset being offered by maker. Must be greater than 0.
              uint256 makerAssetAmount;
              // Amount of takerAsset being bid on by maker. Must be greater than 0.
              uint256 takerAssetAmount;
              // Fee paid to feeRecipient by maker when order is filled.
              uint256 makerFee;
              // Fee paid to feeRecipient by taker when order is filled.
              uint256 takerFee;
              // Timestamp in seconds at which order expires.
              uint256 expirationTimeSeconds;
              // Arbitrary number to facilitate uniqueness of the order's hash.
              uint256 salt;
              // Encoded data that can be decoded by a specified proxy contract when transferring makerAsset.
              // The leading bytes4 references the id of the asset proxy.
              bytes makerAssetData;
              // Encoded data that can be decoded by a specified proxy contract when transferring takerAsset.
              // The leading bytes4 references the id of the asset proxy.
              bytes takerAssetData;
              // Encoded data that can be decoded by a specified proxy contract when transferring makerFeeAsset.
              // The leading bytes4 references the id of the asset proxy.
              bytes makerFeeAssetData;
              // Encoded data that can be decoded by a specified proxy contract when transferring takerFeeAsset.
              // The leading bytes4 references the id of the asset proxy.
              bytes takerFeeAssetData;
          }
          /// @dev V3 `fillOrder()` results.`
          struct FillResults {
              // Total amount of makerAsset(s) filled.
              uint256 makerAssetFilledAmount;
              // Total amount of takerAsset(s) filled.
              uint256 takerAssetFilledAmount;
              // Total amount of fees paid by maker(s) to feeRecipient(s).
              uint256 makerFeePaid;
              // Total amount of fees paid by taker to feeRecipients(s).
              uint256 takerFeePaid;
              // Total amount of fees paid by taker to the staking contract.
              uint256 protocolFeePaid;
          }
          /// @dev Fills the input order.
          /// @param order Order struct containing order specifications.
          /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
          /// @param signature Proof that order has been created by maker.
          /// @return fillResults Amounts filled and fees paid by maker and taker.
          function fillOrder(
              Order calldata order,
              uint256 takerAssetFillAmount,
              bytes calldata signature
          )
              external
              payable
              returns (FillResults memory fillResults);
          /// @dev Returns the protocolFeeMultiplier
          /// @return multiplier The multiplier for protocol fees.
          function protocolFeeMultiplier()
              external
              view
              returns (uint256 multiplier);
          /// @dev Gets an asset proxy.
          /// @param assetProxyId Id of the asset proxy.
          /// @return proxyAddress The asset proxy registered to assetProxyId.
          ///         Returns 0x0 if no proxy is registered.
          function getAssetProxy(bytes4 assetProxyId)
              external
              view
              returns (address proxyAddress);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
      import "../errors/LibTransformERC20RichErrors.sol";
      import "./Transformer.sol";
      import "./LibERC20Transformer.sol";
      /// @dev A transformer that transfers tokens to the taker.
      contract PayTakerTransformer is
          Transformer
      {
          // solhint-disable no-empty-blocks
          using LibRichErrorsV06 for bytes;
          using LibSafeMathV06 for uint256;
          using LibERC20Transformer for IERC20TokenV06;
          /// @dev Transform data to ABI-encode and pass into `transform()`.
          struct TransformData {
              // The tokens to transfer to the taker.
              IERC20TokenV06[] tokens;
              // Amount of each token in `tokens` to transfer to the taker.
              // `uint(-1)` will transfer the entire balance.
              uint256[] amounts;
          }
          /// @dev Maximum uint256 value.
          uint256 private constant MAX_UINT256 = uint256(-1);
          /// @dev Create this contract.
          constructor()
              public
              Transformer()
          {}
          /// @dev Forwards tokens to the taker.
          /// @param taker The taker address (caller of `TransformERC20.transformERC20()`).
          /// @param data_ ABI-encoded `TransformData`, indicating which tokens to transfer.
          /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
          function transform(
              bytes32, // callDataHash,
              address payable taker,
              bytes calldata data_
          )
              external
              override
              returns (bytes4 success)
          {
              TransformData memory data = abi.decode(data_, (TransformData));
              // Transfer tokens directly to the taker.
              for (uint256 i = 0; i < data.tokens.length; ++i) {
                  // The `amounts` array can be shorter than the `tokens` array.
                  // Missing elements are treated as `uint256(-1)`.
                  uint256 amount = data.amounts.length > i ? data.amounts[i] : uint256(-1);
                  if (amount == MAX_UINT256) {
                      amount = data.tokens[i].getTokenBalanceOf(address(this));
                  }
                  if (amount != 0) {
                      data.tokens[i].transformerTransfer(taker, amount);
                  }
              }
              return LibERC20Transformer.TRANSFORMER_SUCCESS;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/IEtherTokenV06.sol";
      import "../errors/LibTransformERC20RichErrors.sol";
      import "./Transformer.sol";
      import "./LibERC20Transformer.sol";
      /// @dev A transformer that wraps or unwraps WETH.
      contract WethTransformer is
          Transformer
      {
          using LibRichErrorsV06 for bytes;
          using LibSafeMathV06 for uint256;
          using LibERC20Transformer for IERC20TokenV06;
          /// @dev Transform data to ABI-encode and pass into `transform()`.
          struct TransformData {
              // The token to wrap/unwrap. Must be either ETH or WETH.
              IERC20TokenV06 token;
              // Amount of `token` to wrap or unwrap.
              // `uint(-1)` will unwrap the entire balance.
              uint256 amount;
          }
          /// @dev The WETH contract address.
          IEtherTokenV06 public immutable weth;
          /// @dev Maximum uint256 value.
          uint256 private constant MAX_UINT256 = uint256(-1);
          /// @dev Construct the transformer and store the WETH address in an immutable.
          /// @param weth_ The weth token.
          constructor(IEtherTokenV06 weth_)
              public
              Transformer()
          {
              weth = weth_;
          }
          /// @dev Wraps and unwraps WETH.
          /// @param data_ ABI-encoded `TransformData`, indicating which token to wrap/umwrap.
          /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
          function transform(
              bytes32, // callDataHash,
              address payable, // taker,
              bytes calldata data_
          )
              external
              override
              returns (bytes4 success)
          {
              TransformData memory data = abi.decode(data_, (TransformData));
              if (!data.token.isTokenETH() && data.token != weth) {
                  LibTransformERC20RichErrors.InvalidTransformDataError(
                      LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_TOKENS,
                      data_
                  ).rrevert();
              }
              uint256 amount = data.amount;
              if (amount == MAX_UINT256) {
                  amount = data.token.getTokenBalanceOf(address(this));
              }
              if (amount != 0) {
                  if (data.token.isTokenETH()) {
                      // Wrap ETH.
                      weth.deposit{value: amount}();
                  } else {
                      // Unwrap WETH.
                      weth.withdraw(amount);
                  }
              }
              return LibERC20Transformer.TRANSFORMER_SUCCESS;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      import "./IERC20TokenV06.sol";
      interface IEtherTokenV06 is
          IERC20TokenV06
      {
          /// @dev Wrap ether.
          function deposit() external payable;
          /// @dev Unwrap ether.
          function withdraw(uint256 amount) external;
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      interface ITestSimpleFunctionRegistryFeature {
          function testFn() external view returns (uint256 id);
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      contract TestCallTarget {
          event CallTargetCalled(
              address context,
              address sender,
              bytes data,
              uint256 value
          );
          bytes4 private constant MAGIC_BYTES = 0x12345678;
          bytes private constant REVERTING_DATA = hex"1337";
          fallback() external payable {
              if (keccak256(msg.data) == keccak256(REVERTING_DATA)) {
                  revert("TestCallTarget/REVERT");
              }
              emit CallTargetCalled(
                  address(this),
                  msg.sender,
                  msg.data,
                  msg.value
              );
              bytes4 rval = MAGIC_BYTES;
              assembly {
                  mstore(0, rval)
                  return(0, 32)
              }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      contract TestDelegateCaller {
          function executeDelegateCall(
              address target,
              bytes calldata callData
          )
              external
          {
              (bool success, bytes memory resultData) = target.delegatecall(callData);
              if (!success) {
                  assembly { revert(add(resultData, 32), mload(resultData)) }
              }
              assembly { return(add(resultData, 32), mload(resultData)) }
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibMathV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
      import "../src/vendor/v3/IExchange.sol";
      import "./TestMintableERC20Token.sol";
      contract TestFillQuoteTransformerExchange {
          struct FillBehavior {
              // How much of the order is filled, in taker asset amount.
              uint256 filledTakerAssetAmount;
              // Scaling for maker assets minted, in 1e18.
              uint256 makerAssetMintRatio;
          }
          uint256 private constant PROTOCOL_FEE_MULTIPLIER = 1337;
          using LibSafeMathV06 for uint256;
          function fillOrder(
              IExchange.Order calldata order,
              uint256 takerAssetFillAmount,
              bytes calldata signature
          )
              external
              payable
              returns (IExchange.FillResults memory fillResults)
          {
              require(
                  signature.length != 0,
                  "TestFillQuoteTransformerExchange/INVALID_SIGNATURE"
              );
              // The signature is the ABI-encoded FillBehavior data.
              FillBehavior memory behavior = abi.decode(signature, (FillBehavior));
              uint256 protocolFee = PROTOCOL_FEE_MULTIPLIER * tx.gasprice;
              require(
                  msg.value == protocolFee,
                  "TestFillQuoteTransformerExchange/INSUFFICIENT_PROTOCOL_FEE"
              );
              // Return excess protocol fee.
              msg.sender.transfer(msg.value - protocolFee);
              // Take taker tokens.
              TestMintableERC20Token takerToken = _getTokenFromAssetData(order.takerAssetData);
              takerAssetFillAmount = LibSafeMathV06.min256(
                  order.takerAssetAmount.safeSub(behavior.filledTakerAssetAmount),
                  takerAssetFillAmount
              );
              require(
                  takerToken.getSpendableAmount(msg.sender, address(this)) >= takerAssetFillAmount,
                  "TestFillQuoteTransformerExchange/INSUFFICIENT_TAKER_FUNDS"
              );
              takerToken.transferFrom(msg.sender, order.makerAddress, takerAssetFillAmount);
              // Mint maker tokens.
              uint256 makerAssetFilledAmount = LibMathV06.getPartialAmountFloor(
                  takerAssetFillAmount,
                  order.takerAssetAmount,
                  order.makerAssetAmount
              );
              TestMintableERC20Token makerToken = _getTokenFromAssetData(order.makerAssetData);
              makerToken.mint(
                  msg.sender,
                  LibMathV06.getPartialAmountFloor(
                      behavior.makerAssetMintRatio,
                      1e18,
                      makerAssetFilledAmount
                  )
              );
              // Take taker fee.
              TestMintableERC20Token takerFeeToken = _getTokenFromAssetData(order.takerFeeAssetData);
              uint256 takerFee = LibMathV06.getPartialAmountFloor(
                  takerAssetFillAmount,
                  order.takerAssetAmount,
                  order.takerFee
              );
              require(
                  takerFeeToken.getSpendableAmount(msg.sender, address(this)) >= takerFee,
                  "TestFillQuoteTransformerExchange/INSUFFICIENT_TAKER_FEE_FUNDS"
              );
              takerFeeToken.transferFrom(msg.sender, order.feeRecipientAddress, takerFee);
              fillResults.makerAssetFilledAmount = makerAssetFilledAmount;
              fillResults.takerAssetFilledAmount = takerAssetFillAmount;
              fillResults.makerFeePaid = uint256(-1);
              fillResults.takerFeePaid = takerFee;
              fillResults.protocolFeePaid = protocolFee;
          }
          function encodeBehaviorData(FillBehavior calldata behavior)
              external
              pure
              returns (bytes memory encoded)
          {
              return abi.encode(behavior);
          }
          function protocolFeeMultiplier()
              external
              pure
              returns (uint256)
          {
              return PROTOCOL_FEE_MULTIPLIER;
          }
          function getAssetProxy(bytes4)
              external
              view
              returns (address)
          {
              return address(this);
          }
          function _getTokenFromAssetData(bytes memory assetData)
              private
              pure
              returns (TestMintableERC20Token token)
          {
              return TestMintableERC20Token(LibBytesV06.readAddress(assetData, 16));
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      contract TestMintableERC20Token {
          mapping(address => uint256) public balanceOf;
          mapping(address => mapping(address => uint256)) public allowance;
          function transfer(address to, uint256 amount)
              external
              virtual
              returns (bool)
          {
              return transferFrom(msg.sender, to, amount);
          }
          function approve(address spender, uint256 amount)
              external
              virtual
              returns (bool)
          {
              allowance[msg.sender][spender] = amount;
              return true;
          }
          function mint(address owner, uint256 amount)
              external
              virtual
          {
              balanceOf[owner] += amount;
          }
          function burn(address owner, uint256 amount)
              external
              virtual
          {
              require(balanceOf[owner] >= amount, "TestMintableERC20Token/INSUFFICIENT_FUNDS");
              balanceOf[owner] -= amount;
          }
          function transferFrom(address from, address to, uint256 amount)
              public
              virtual
              returns (bool)
          {
              if (from != msg.sender) {
                  require(
                      allowance[from][msg.sender] >= amount,
                      "TestMintableERC20Token/INSUFFICIENT_ALLOWANCE"
                  );
                  allowance[from][msg.sender] -= amount;
              }
              require(balanceOf[from] >= amount, "TestMintableERC20Token/INSUFFICIENT_FUNDS");
              balanceOf[from] -= amount;
              balanceOf[to] += amount;
              return true;
          }
          function getSpendableAmount(address owner, address spender)
              external
              view
              returns (uint256)
          {
              return balanceOf[owner] < allowance[owner][spender]
                  ? balanceOf[owner]
                  : allowance[owner][spender];
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/transformers/IERC20Transformer.sol";
      import "./TestMintableERC20Token.sol";
      import "./TestTransformerHost.sol";
      contract TestFillQuoteTransformerHost is
          TestTransformerHost
      {
          function executeTransform(
              IERC20Transformer transformer,
              TestMintableERC20Token inputToken,
              uint256 inputTokenAmount,
              bytes calldata data
          )
              external
              payable
          {
              if (inputTokenAmount != 0) {
                  inputToken.mint(address(this), inputTokenAmount);
              }
              // Have to make this call externally because transformers aren't payable.
              this.rawExecuteTransform(transformer, bytes32(0), msg.sender, data);
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "../src/transformers/IERC20Transformer.sol";
      import "../src/transformers/LibERC20Transformer.sol";
      contract TestTransformerHost {
          using LibERC20Transformer for IERC20TokenV06;
          using LibRichErrorsV06 for bytes;
          function rawExecuteTransform(
              IERC20Transformer transformer,
              bytes32 callDataHash,
              address taker,
              bytes calldata data
          )
              external
          {
              (bool _success, bytes memory resultData) =
                  address(transformer).delegatecall(abi.encodeWithSelector(
                      transformer.transform.selector,
                      callDataHash,
                      taker,
                      data
                  ));
              if (!_success) {
                  resultData.rrevert();
              }
              require(
                  abi.decode(resultData, (bytes4)) == LibERC20Transformer.TRANSFORMER_SUCCESS,
                  "TestTransformerHost/INVALID_TRANSFORMER_RESULT"
              );
          }
          // solhint-disable
          receive() external payable {}
          // solhint-enable
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/ZeroEx.sol";
      import "../src/features/IBootstrap.sol";
      import "../src/migrations/FullMigration.sol";
      contract TestFullMigration is
          FullMigration
      {
          address public dieRecipient;
          // solhint-disable-next-line no-empty-blocks
          constructor(address payable deployer) public FullMigration(deployer) {}
          function die(address payable ethRecipient) external override {
              dieRecipient = ethRecipient;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/ZeroEx.sol";
      import "../src/features/IBootstrap.sol";
      import "../src/migrations/InitialMigration.sol";
      contract TestInitialMigration is
          InitialMigration
      {
          address public bootstrapFeature;
          address public dieRecipient;
          // solhint-disable-next-line no-empty-blocks
          constructor(address deployer) public InitialMigration(deployer) {}
          function callBootstrap(ZeroEx zeroEx) external {
              IBootstrap(address(zeroEx)).bootstrap(address(this), new bytes(0));
          }
          function bootstrap(address owner, BootstrapFeatures memory features)
              public
              override
              returns (bytes4 success)
          {
              success = InitialMigration.bootstrap(owner, features);
              // Snoop the bootstrap feature contract.
              bootstrapFeature = ZeroEx(address(uint160(address(this))))
                  .getFunctionImplementation(IBootstrap.bootstrap.selector);
          }
          function die(address payable ethRecipient) public override {
              dieRecipient = ethRecipient;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/migrations/LibMigrate.sol";
      import "../src/features/IOwnable.sol";
      contract TestMigrator {
          event TestMigrateCalled(
              bytes callData,
              address owner
          );
          function succeedingMigrate() external returns (bytes4 success) {
              emit TestMigrateCalled(
                  msg.data,
                  IOwnable(address(this)).owner()
              );
              return LibMigrate.MIGRATE_SUCCESS;
          }
          function failingMigrate() external returns (bytes4 success) {
              emit TestMigrateCalled(
                  msg.data,
                  IOwnable(address(this)).owner()
              );
              return 0xdeadbeef;
          }
          function revertingMigrate() external pure {
              revert("OOPSIE");
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "../src/transformers/IERC20Transformer.sol";
      import "../src/transformers/LibERC20Transformer.sol";
      import "./TestMintableERC20Token.sol";
      contract TestMintTokenERC20Transformer is
          IERC20Transformer
      {
          struct TransformData {
              IERC20TokenV06 inputToken;
              TestMintableERC20Token outputToken;
              uint256 burnAmount;
              uint256 mintAmount;
              uint256 feeAmount;
          }
          event MintTransform(
              address context,
              address caller,
              bytes32 callDataHash,
              address taker,
              bytes data,
              uint256 inputTokenBalance,
              uint256 ethBalance
          );
          function transform(
              bytes32 callDataHash,
              address payable taker,
              bytes calldata data_
          )
              external
              override
              returns (bytes4 success)
          {
              TransformData memory data = abi.decode(data_, (TransformData));
              emit MintTransform(
                  address(this),
                  msg.sender,
                  callDataHash,
                  taker,
                  data_,
                  data.inputToken.balanceOf(address(this)),
                  address(this).balance
              );
              // "Burn" input tokens.
              data.inputToken.transfer(address(0), data.burnAmount);
              // Mint output tokens.
              if (LibERC20Transformer.isTokenETH(IERC20TokenV06(address(data.outputToken)))) {
                  taker.transfer(data.mintAmount);
              } else {
                  data.outputToken.mint(
                      taker,
                      data.mintAmount
                  );
                  // Burn fees from output.
                  data.outputToken.burn(taker, data.feeAmount);
              }
              return LibERC20Transformer.TRANSFORMER_SUCCESS;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/fixins/FixinCommon.sol";
      contract TestSimpleFunctionRegistryFeatureImpl1 is
          FixinCommon
      {
          function testFn()
              external
              pure
              returns (uint256 id)
          {
              return 1337;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/fixins/FixinCommon.sol";
      contract TestSimpleFunctionRegistryFeatureImpl2 is
          FixinCommon
      {
          function testFn()
              external
              pure
              returns (uint256 id)
          {
              return 1338;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/features/TokenSpender.sol";
      contract TestTokenSpender is
          TokenSpender
      {
          modifier onlySelf() override {
              _;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "./TestMintableERC20Token.sol";
      contract TestTokenSpenderERC20Token is
          TestMintableERC20Token
      {
          event TransferFromCalled(
              address sender,
              address from,
              address to,
              uint256 amount
          );
          // `transferFrom()` behavior depends on the value of `amount`.
          uint256 constant private EMPTY_RETURN_AMOUNT = 1337;
          uint256 constant private FALSE_RETURN_AMOUNT = 1338;
          uint256 constant private REVERT_RETURN_AMOUNT = 1339;
          function transferFrom(address from, address to, uint256 amount)
              public
              override
              returns (bool)
          {
              emit TransferFromCalled(msg.sender, from, to, amount);
              if (amount == EMPTY_RETURN_AMOUNT) {
                  assembly { return(0, 0) }
              }
              if (amount == FALSE_RETURN_AMOUNT) {
                  return false;
              }
              if (amount == REVERT_RETURN_AMOUNT) {
                  revert("TestTokenSpenderERC20Token/Revert");
              }
              return true;
          }
          function setBalanceAndAllowanceOf(
              address owner,
              uint256 balance,
              address spender,
              uint256 allowance_
          )
              external
          {
              balanceOf[owner] = balance;
              allowance[owner][spender] = allowance_;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/features/TransformERC20.sol";
      contract TestTransformERC20 is
          TransformERC20
      {
          // solhint-disable no-empty-blocks
          constructor()
              TransformERC20()
              public
          {}
          modifier onlySelf() override {
              _;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/transformers/Transformer.sol";
      import "../src/transformers/LibERC20Transformer.sol";
      contract TestTransformerBase is
          Transformer
      {
          function transform(
              bytes32,
              address payable,
              bytes calldata
          )
              external
              override
              returns (bytes4 success)
          {
              return LibERC20Transformer.TRANSFORMER_SUCCESS;
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/transformers/LibERC20Transformer.sol";
      contract TestTransformerDeployerTransformer {
          address payable public immutable deployer;
          constructor() public payable {
              deployer = msg.sender;
          }
          modifier onlyDeployer() {
              require(msg.sender == deployer, "TestTransformerDeployerTransformer/ONLY_DEPLOYER");
              _;
          }
          function die()
              external
              onlyDeployer
          {
              selfdestruct(deployer);
          }
          function isDeployedByDeployer(uint32 nonce)
              external
              view
              returns (bool)
          {
              return LibERC20Transformer.getDeployedAddress(deployer, nonce) == address(this);
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "./TestMintableERC20Token.sol";
      contract TestWeth is
          TestMintableERC20Token
      {
          function deposit()
              external
              payable
          {
              this.mint(msg.sender, msg.value);
          }
          function withdraw(uint256 amount)
              external
          {
              require(balanceOf[msg.sender] >= amount, "TestWeth/INSUFFICIENT_FUNDS");
              balanceOf[msg.sender] -= amount;
              msg.sender.transfer(amount);
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/transformers/IERC20Transformer.sol";
      import "./TestMintableERC20Token.sol";
      import "./TestTransformerHost.sol";
      import "./TestWeth.sol";
      contract TestWethTransformerHost is
          TestTransformerHost
      {
          // solhint-disable
          TestWeth private immutable _weth;
          // solhint-enable
          constructor(TestWeth weth) public {
              _weth = weth;
          }
          function executeTransform(
              uint256 wethAmount,
              IERC20Transformer transformer,
              bytes calldata data
          )
              external
              payable
          {
              if (wethAmount != 0) {
                  _weth.deposit{value: wethAmount}();
              }
              // Have to make this call externally because transformers aren't payable.
              this.rawExecuteTransform(transformer, bytes32(0), msg.sender, data);
          }
      }
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "../src/fixins/FixinCommon.sol";
      import "../src/ZeroEx.sol";
      contract TestZeroExFeature is
          FixinCommon
      {
          event PayableFnCalled(uint256 value);
          event NotPayableFnCalled();
          function payableFn()
              external
              payable
          {
              emit PayableFnCalled(msg.value);
          }
          function notPayableFn()
              external
          {
              emit NotPayableFnCalled();
          }
          // solhint-disable no-empty-blocks
          function unimplmentedFn()
              external
          {}
          function internalFn()
              external
              onlySelf
          {}
      }
      

      File 2 of 3: WifeBoredApe
      // SPDX-License-Identifier: MIT
      
      /**
      NobleBored NFT
      */
      
      
      
      pragma solidity ^0.8.0;
      
      /**
       * @dev Provides information about the current execution context, including the
       * sender of the transaction and its data. While these are generally available
       * via msg.sender and msg.data, they should not be accessed in such a direct
       * manner, since when dealing with meta-transactions the account sending and
       * paying for execution may not be the actual sender (as far as an application
       * is concerned).
       *
       * This contract is only required for intermediate, library-like contracts.
       */
      abstract contract Context {
          function _msgSender() internal view virtual returns (address) {
              return msg.sender;
          }
      
          function _msgData() internal view virtual returns (bytes calldata) {
              return msg.data;
          }
      }
      
      // File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/access/Ownable.sol
      
      
      
      pragma solidity ^0.8.0;
      
      
      /**
       * @dev Contract module which provides a basic access control mechanism, where
       * there is an account (an owner) that can be granted exclusive access to
       * specific functions.
       *
       * By default, the owner account will be the one that deploys the contract. This
       * can later be changed with {transferOwnership}.
       *
       * This module is used through inheritance. It will make available the modifier
       * `onlyOwner`, which can be applied to your functions to restrict their use to
       * the owner.
       */
      abstract contract Ownable is Context {
          address private _owner;
      
          event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
      
          /**
           * @dev Initializes the contract setting the deployer as the initial owner.
           */
          constructor() {
              _transferOwnership(_msgSender());
          }
      
          /**
           * @dev Returns the address of the current owner.
           */
          function owner() public view virtual returns (address) {
              return _owner;
          }
      
          /**
           * @dev Throws if called by any account other than the owner.
           */
          modifier onlyOwner() {
              require(owner() == _msgSender(), "Ownable: caller is not the owner");
              _;
          }
      
          /**
           * @dev Leaves the contract without owner. It will not be possible to call
           * `onlyOwner` functions anymore. Can only be called by the current owner.
           *
           * NOTE: Renouncing ownership will leave the contract without an owner,
           * thereby removing any functionality that is only available to the owner.
           */
          function renounceOwnership() public virtual onlyOwner {
              _transferOwnership(address(0));
          }
      
          /**
           * @dev Transfers ownership of the contract to a new account (`newOwner`).
           * Can only be called by the current owner.
           */
          function transferOwnership(address newOwner) public virtual onlyOwner {
              require(newOwner != address(0), "Ownable: new owner is the zero address");
              _transferOwnership(newOwner);
          }
      
          /**
           * @dev Transfers ownership of the contract to a new account (`newOwner`).
           * Internal function without access restriction.
           */
          function _transferOwnership(address newOwner) internal virtual {
              address oldOwner = _owner;
              _owner = newOwner;
              emit OwnershipTransferred(oldOwner, newOwner);
          }
      }
      
      // File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Address.sol
      
      
      
      pragma solidity ^0.8.0;
      
      /**
       * @dev Collection of functions related to the address type
       */
      library Address {
          /**
           * @dev Returns true if `account` is a contract.
           *
           * [IMPORTANT]
           * ====
           * It is unsafe to assume that an address for which this function returns
           * false is an externally-owned account (EOA) and not a contract.
           *
           * Among others, `isContract` will return false for the following
           * types of addresses:
           *
           *  - an externally-owned account
           *  - a contract in construction
           *  - an address where a contract will be created
           *  - an address where a contract lived, but was destroyed
           * ====
           */
          function isContract(address account) internal view returns (bool) {
              // This method relies on extcodesize, which returns 0 for contracts in
              // construction, since the code is only stored at the end of the
              // constructor execution.
      
              uint256 size;
              assembly {
                  size := extcodesize(account)
              }
              return size > 0;
          }
      
          /**
           * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
           * `recipient`, forwarding all available gas and reverting on errors.
           *
           * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
           * of certain opcodes, possibly making contracts go over the 2300 gas limit
           * imposed by `transfer`, making them unable to receive funds via
           * `transfer`. {sendValue} removes this limitation.
           *
           * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
           *
           * IMPORTANT: because control is transferred to `recipient`, care must be
           * taken to not create reentrancy vulnerabilities. Consider using
           * {ReentrancyGuard} or the
           * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
           */
          function sendValue(address payable recipient, uint256 amount) internal {
              require(address(this).balance >= amount, "Address: insufficient balance");
      
              (bool success, ) = recipient.call{value: amount}("");
              require(success, "Address: unable to send value, recipient may have reverted");
          }
      
          /**
           * @dev Performs a Solidity function call using a low level `call`. A
           * plain `call` is an unsafe replacement for a function call: use this
           * function instead.
           *
           * If `target` reverts with a revert reason, it is bubbled up by this
           * function (like regular Solidity function calls).
           *
           * Returns the raw returned data. To convert to the expected return value,
           * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
           *
           * Requirements:
           *
           * - `target` must be a contract.
           * - calling `target` with `data` must not revert.
           *
           * _Available since v3.1._
           */
          function functionCall(address target, bytes memory data) internal returns (bytes memory) {
              return functionCall(target, data, "Address: low-level call failed");
          }
      
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
           * `errorMessage` as a fallback revert reason when `target` reverts.
           *
           * _Available since v3.1._
           */
          function functionCall(
              address target,
              bytes memory data,
              string memory errorMessage
          ) internal returns (bytes memory) {
              return functionCallWithValue(target, data, 0, errorMessage);
          }
      
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but also transferring `value` wei to `target`.
           *
           * Requirements:
           *
           * - the calling contract must have an ETH balance of at least `value`.
           * - the called Solidity function must be `payable`.
           *
           * _Available since v3.1._
           */
          function functionCallWithValue(
              address target,
              bytes memory data,
              uint256 value
          ) internal returns (bytes memory) {
              return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
          }
      
          /**
           * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
           * with `errorMessage` as a fallback revert reason when `target` reverts.
           *
           * _Available since v3.1._
           */
          function functionCallWithValue(
              address target,
              bytes memory data,
              uint256 value,
              string memory errorMessage
          ) internal returns (bytes memory) {
              require(address(this).balance >= value, "Address: insufficient balance for call");
              require(isContract(target), "Address: call to non-contract");
      
              (bool success, bytes memory returndata) = target.call{value: value}(data);
              return verifyCallResult(success, returndata, errorMessage);
          }
      
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but performing a static call.
           *
           * _Available since v3.3._
           */
          function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
              return functionStaticCall(target, data, "Address: low-level static call failed");
          }
      
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
           * but performing a static call.
           *
           * _Available since v3.3._
           */
          function functionStaticCall(
              address target,
              bytes memory data,
              string memory errorMessage
          ) internal view returns (bytes memory) {
              require(isContract(target), "Address: static call to non-contract");
      
              (bool success, bytes memory returndata) = target.staticcall(data);
              return verifyCallResult(success, returndata, errorMessage);
          }
      
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but performing a delegate call.
           *
           * _Available since v3.4._
           */
          function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
              return functionDelegateCall(target, data, "Address: low-level delegate call failed");
          }
      
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
           * but performing a delegate call.
           *
           * _Available since v3.4._
           */
          function functionDelegateCall(
              address target,
              bytes memory data,
              string memory errorMessage
          ) internal returns (bytes memory) {
              require(isContract(target), "Address: delegate call to non-contract");
      
              (bool success, bytes memory returndata) = target.delegatecall(data);
              return verifyCallResult(success, returndata, errorMessage);
          }
      
          /**
           * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
           * revert reason using the provided one.
           *
           * _Available since v4.3._
           */
          function verifyCallResult(
              bool success,
              bytes memory returndata,
              string memory errorMessage
          ) internal pure returns (bytes memory) {
              if (success) {
                  return returndata;
              } else {
                  // Look for revert reason and bubble it up if present
                  if (returndata.length > 0) {
                      // The easiest way to bubble the revert reason is using memory via assembly
      
                      assembly {
                          let returndata_size := mload(returndata)
                          revert(add(32, returndata), returndata_size)
                      }
                  } else {
                      revert(errorMessage);
                  }
              }
          }
      }
      
      // File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/introspection/IERC165.sol
      
      
      
      pragma solidity ^0.8.0;
      
      /**
       * @dev Interface of the ERC165 standard, as defined in the
       * https://eips.ethereum.org/EIPS/eip-165[EIP].
       *
       * Implementers can declare support of contract interfaces, which can then be
       * queried by others ({ERC165Checker}).
       *
       * For an implementation, see {ERC165}.
       */
      interface IERC165 {
          /**
           * @dev Returns true if this contract implements the interface defined by
           * `interfaceId`. See the corresponding
           * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
           * to learn more about how these ids are created.
           *
           * This function call must use less than 30 000 gas.
           */
          function supportsInterface(bytes4 interfaceId) external view returns (bool);
      }
      
      // File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/introspection/ERC165.sol
      
      
      
      pragma solidity ^0.8.0;
      
      
      /**
       * @dev Implementation of the {IERC165} interface.
       *
       * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
       * for the additional interface id that will be supported. For example:
       *
       * ```solidity
       * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
       *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
       * }
       * ```
       *
       * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
       */
      abstract contract ERC165 is IERC165 {
          /**
           * @dev See {IERC165-supportsInterface}.
           */
          function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
              return interfaceId == type(IERC165).interfaceId;
          }
      }
      
      // File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC1155/IERC1155Receiver.sol
      
      
      
      pragma solidity ^0.8.0;
      
      
      /**
       * @dev _Available since v3.1._
       */
      interface IERC1155Receiver is IERC165 {
          /**
              @dev Handles the receipt of a single ERC1155 token type. This function is
              called at the end of a `safeTransferFrom` after the balance has been updated.
              To accept the transfer, this must return
              `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
              (i.e. 0xf23a6e61, or its own function selector).
              @param operator The address which initiated the transfer (i.e. msg.sender)
              @param from The address which previously owned the token
              @param id The ID of the token being transferred
              @param value The amount of tokens being transferred
              @param data Additional data with no specified format
              @return `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))` if transfer is allowed
          */
          function onERC1155Received(
              address operator,
              address from,
              uint256 id,
              uint256 value,
              bytes calldata data
          ) external returns (bytes4);
      
          /**
              @dev Handles the receipt of a multiple ERC1155 token types. This function
              is called at the end of a `safeBatchTransferFrom` after the balances have
              been updated. To accept the transfer(s), this must return
              `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
              (i.e. 0xbc197c81, or its own function selector).
              @param operator The address which initiated the batch transfer (i.e. msg.sender)
              @param from The address which previously owned the token
              @param ids An array containing ids of each token being transferred (order and length must match values array)
              @param values An array containing amounts of each token being transferred (order and length must match ids array)
              @param data Additional data with no specified format
              @return `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))` if transfer is allowed
          */
          function onERC1155BatchReceived(
              address operator,
              address from,
              uint256[] calldata ids,
              uint256[] calldata values,
              bytes calldata data
          ) external returns (bytes4);
      }
      
      // File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC1155/IERC1155.sol
      
      
      
      pragma solidity ^0.8.0;
      
      
      /**
       * @dev Required interface of an ERC1155 compliant contract, as defined in the
       * https://eips.ethereum.org/EIPS/eip-1155[EIP].
       *
       * _Available since v3.1._
       */
      interface IERC1155 is IERC165 {
          /**
           * @dev Emitted when `value` tokens of token type `id` are transferred from `from` to `to` by `operator`.
           */
          event TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value);
      
          /**
           * @dev Equivalent to multiple {TransferSingle} events, where `operator`, `from` and `to` are the same for all
           * transfers.
           */
          event TransferBatch(
              address indexed operator,
              address indexed from,
              address indexed to,
              uint256[] ids,
              uint256[] values
          );
      
          /**
           * @dev Emitted when `account` grants or revokes permission to `operator` to transfer their tokens, according to
           * `approved`.
           */
          event ApprovalForAll(address indexed account, address indexed operator, bool approved);
      
          /**
           * @dev Emitted when the URI for token type `id` changes to `value`, if it is a non-programmatic URI.
           *
           * If an {URI} event was emitted for `id`, the standard
           * https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[guarantees] that `value` will equal the value
           * returned by {IERC1155MetadataURI-uri}.
           */
          event URI(string value, uint256 indexed id);
      
          /**
           * @dev Returns the amount of tokens of token type `id` owned by `account`.
           *
           * Requirements:
           *
           * - `account` cannot be the zero address.
           */
          function balanceOf(address account, uint256 id) external view returns (uint256);
      
          /**
           * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {balanceOf}.
           *
           * Requirements:
           *
           * - `accounts` and `ids` must have the same length.
           */
          function balanceOfBatch(address[] calldata accounts, uint256[] calldata ids)
              external
              view
              returns (uint256[] memory);
      
          /**
           * @dev Grants or revokes permission to `operator` to transfer the caller's tokens, according to `approved`,
           *
           * Emits an {ApprovalForAll} event.
           *
           * Requirements:
           *
           * - `operator` cannot be the caller.
           */
          function setApprovalForAll(address operator, bool approved) external;
      
          /**
           * @dev Returns true if `operator` is approved to transfer ``account``'s tokens.
           *
           * See {setApprovalForAll}.
           */
          function isApprovedForAll(address account, address operator) external view returns (bool);
      
          /**
           * @dev Transfers `amount` tokens of token type `id` from `from` to `to`.
           *
           * Emits a {TransferSingle} event.
           *
           * Requirements:
           *
           * - `to` cannot be the zero address.
           * - If the caller is not `from`, it must be have been approved to spend ``from``'s tokens via {setApprovalForAll}.
           * - `from` must have a balance of tokens of type `id` of at least `amount`.
           * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
           * acceptance magic value.
           */
          function safeTransferFrom(
              address from,
              address to,
              uint256 id,
              uint256 amount,
              bytes calldata data
          ) external;
      
          /**
           * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {safeTransferFrom}.
           *
           * Emits a {TransferBatch} event.
           *
           * Requirements:
           *
           * - `ids` and `amounts` must have the same length.
           * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
           * acceptance magic value.
           */
          function safeBatchTransferFrom(
              address from,
              address to,
              uint256[] calldata ids,
              uint256[] calldata amounts,
              bytes calldata data
          ) external;
      }
      
      // File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC1155/extensions/IERC1155MetadataURI.sol
      
      
      
      pragma solidity ^0.8.0;
      
      
      /**
       * @dev Interface of the optional ERC1155MetadataExtension interface, as defined
       * in the https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[EIP].
       *
       * _Available since v3.1._
       */
      interface IERC1155MetadataURI is IERC1155 {
          /**
           * @dev Returns the URI for token type `id`.
           *
           * If the `\{id\}` substring is present in the URI, it must be replaced by
           * clients with the actual token type ID.
           */
          function uri(uint256 id) external view returns (string memory);
      }
      
      // File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC1155/ERC1155.sol
      
      
      
      pragma solidity ^0.8.0;
      
      
      
      
      
      
      
      /**
       * @dev Implementation of the basic standard multi-token.
       * See https://eips.ethereum.org/EIPS/eip-1155
       * Originally based on code by Enjin: https://github.com/enjin/erc-1155
       *
       * _Available since v3.1._
       */
      contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
          using Address for address;
      
          // Mapping from token ID to account balances
          mapping(uint256 => mapping(address => uint256)) private _balances;
      
          // Mapping from account to operator approvals
          mapping(address => mapping(address => bool)) private _operatorApprovals;
      
          // Used as the URI for all token types by relying on ID substitution, e.g. https://token-cdn-domain/{id}.json
          string private _uri;
      
          /**
           * @dev See {_setURI}.
           */
          constructor(string memory uri_) {
              _setURI(uri_);
          }
      
          /**
           * @dev See {IERC165-supportsInterface}.
           */
          function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
              return
                  interfaceId == type(IERC1155).interfaceId ||
                  interfaceId == type(IERC1155MetadataURI).interfaceId ||
                  super.supportsInterface(interfaceId);
          }
      
          /**
           * @dev See {IERC1155MetadataURI-uri}.
           *
           * This implementation returns the same URI for *all* token types. It relies
           * on the token type ID substitution mechanism
           * https://eips.ethereum.org/EIPS/eip-1155#metadata[defined in the EIP].
           *
           * Clients calling this function must replace the `\{id\}` substring with the
           * actual token type ID.
           */
          function uri(uint256) public view virtual override returns (string memory) {
              return _uri;
          }
      
          /**
           * @dev See {IERC1155-balanceOf}.
           *
           * Requirements:
           *
           * - `account` cannot be the zero address.
           */
          function balanceOf(address account, uint256 id) public view virtual override returns (uint256) {
              require(account != address(0), "ERC1155: balance query for the zero address");
              return _balances[id][account];
          }
      
          /**
           * @dev See {IERC1155-balanceOfBatch}.
           *
           * Requirements:
           *
           * - `accounts` and `ids` must have the same length.
           */
          function balanceOfBatch(address[] memory accounts, uint256[] memory ids)
              public
              view
              virtual
              override
              returns (uint256[] memory)
          {
              require(accounts.length == ids.length, "ERC1155: accounts and ids length mismatch");
      
              uint256[] memory batchBalances = new uint256[](accounts.length);
      
              for (uint256 i = 0; i < accounts.length; ++i) {
                  batchBalances[i] = balanceOf(accounts[i], ids[i]);
              }
      
              return batchBalances;
          }
      
          /**
           * @dev See {IERC1155-setApprovalForAll}.
           */
          function setApprovalForAll(address operator, bool approved) public virtual override {
              _setApprovalForAll(_msgSender(), operator, approved);
          }
      
          /**
           * @dev See {IERC1155-isApprovedForAll}.
           */
          function isApprovedForAll(address account, address operator) public view virtual override returns (bool) {
              return _operatorApprovals[account][operator];
          }
      
          /**
           * @dev See {IERC1155-safeTransferFrom}.
           */
          function safeTransferFrom(
              address from,
              address to,
              uint256 id,
              uint256 amount,
              bytes memory data
          ) public virtual override {
              require(
                  from == _msgSender() || isApprovedForAll(from, _msgSender()),
                  "ERC1155: caller is not owner nor approved"
              );
              _safeTransferFrom(from, to, id, amount, data);
          }
      
          /**
           * @dev See {IERC1155-safeBatchTransferFrom}.
           */
          function safeBatchTransferFrom(
              address from,
              address to,
              uint256[] memory ids,
              uint256[] memory amounts,
              bytes memory data
          ) public virtual override {
              require(
                  from == _msgSender() || isApprovedForAll(from, _msgSender()),
                  "ERC1155: transfer caller is not owner nor approved"
              );
              _safeBatchTransferFrom(from, to, ids, amounts, data);
          }
      
          /**
           * @dev Transfers `amount` tokens of token type `id` from `from` to `to`.
           *
           * Emits a {TransferSingle} event.
           *
           * Requirements:
           *
           * - `to` cannot be the zero address.
           * - `from` must have a balance of tokens of type `id` of at least `amount`.
           * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
           * acceptance magic value.
           */
          function _safeTransferFrom(
              address from,
              address to,
              uint256 id,
              uint256 amount,
              bytes memory data
          ) internal virtual {
              require(to != address(0), "ERC1155: transfer to the zero address");
      
              address operator = _msgSender();
      
              _beforeTokenTransfer(operator, from, to, _asSingletonArray(id), _asSingletonArray(amount), data);
      
              uint256 fromBalance = _balances[id][from];
              require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
              unchecked {
                  _balances[id][from] = fromBalance - amount;
              }
              _balances[id][to] += amount;
      
              emit TransferSingle(operator, from, to, id, amount);
      
              _doSafeTransferAcceptanceCheck(operator, from, to, id, amount, data);
          }
      
          /**
           * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {_safeTransferFrom}.
           *
           * Emits a {TransferBatch} event.
           *
           * Requirements:
           *
           * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
           * acceptance magic value.
           */
          function _safeBatchTransferFrom(
              address from,
              address to,
              uint256[] memory ids,
              uint256[] memory amounts,
              bytes memory data
          ) internal virtual {
              require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");
              require(to != address(0), "ERC1155: transfer to the zero address");
      
              address operator = _msgSender();
      
              _beforeTokenTransfer(operator, from, to, ids, amounts, data);
      
              for (uint256 i = 0; i < ids.length; ++i) {
                  uint256 id = ids[i];
                  uint256 amount = amounts[i];
      
                  uint256 fromBalance = _balances[id][from];
                  require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
                  unchecked {
                      _balances[id][from] = fromBalance - amount;
                  }
                  _balances[id][to] += amount;
              }
      
              emit TransferBatch(operator, from, to, ids, amounts);
      
              _doSafeBatchTransferAcceptanceCheck(operator, from, to, ids, amounts, data);
          }
      
          /**
           * @dev Sets a new URI for all token types, by relying on the token type ID
           * substitution mechanism
           * https://eips.ethereum.org/EIPS/eip-1155#metadata[defined in the EIP].
           *
           * By this mechanism, any occurrence of the `\{id\}` substring in either the
           * URI or any of the amounts in the JSON file at said URI will be replaced by
           * clients with the token type ID.
           *
           * For example, the `https://token-cdn-domain/\{id\}.json` URI would be
           * interpreted by clients as
           * `https://token-cdn-domain/000000000000000000000000000000000000000000000000000000000004cce0.json`
           * for token type ID 0x4cce0.
           *
           * See {uri}.
           *
           * Because these URIs cannot be meaningfully represented by the {URI} event,
           * this function emits no events.
           */
          function _setURI(string memory newuri) internal virtual {
              _uri = newuri;
          }
      
          /**
           * @dev Creates `amount` tokens of token type `id`, and assigns them to `to`.
           *
           * Emits a {TransferSingle} event.
           *
           * Requirements:
           *
           * - `to` cannot be the zero address.
           * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
           * acceptance magic value.
           */
          function _mint(
              address to,
              uint256 id,
              uint256 amount,
              bytes memory data
          ) internal virtual {
              require(to != address(0), "ERC1155: mint to the zero address");
      
              address operator = _msgSender();
      
              _beforeTokenTransfer(operator, address(0), to, _asSingletonArray(id), _asSingletonArray(amount), data);
      
              _balances[id][to] += amount;
              emit TransferSingle(operator, address(0), to, id, amount);
      
              _doSafeTransferAcceptanceCheck(operator, address(0), to, id, amount, data);
          }
      
          /**
           * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {_mint}.
           *
           * Requirements:
           *
           * - `ids` and `amounts` must have the same length.
           * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
           * acceptance magic value.
           */
          function _mintBatch(
              address to,
              uint256[] memory ids,
              uint256[] memory amounts,
              bytes memory data
          ) internal virtual {
              require(to != address(0), "ERC1155: mint to the zero address");
              require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");
      
              address operator = _msgSender();
      
              _beforeTokenTransfer(operator, address(0), to, ids, amounts, data);
      
              for (uint256 i = 0; i < ids.length; i++) {
                  _balances[ids[i]][to] += amounts[i];
              }
      
              emit TransferBatch(operator, address(0), to, ids, amounts);
      
              _doSafeBatchTransferAcceptanceCheck(operator, address(0), to, ids, amounts, data);
          }
      
          /**
           * @dev Destroys `amount` tokens of token type `id` from `from`
           *
           * Requirements:
           *
           * - `from` cannot be the zero address.
           * - `from` must have at least `amount` tokens of token type `id`.
           */
          function _burn(
              address from,
              uint256 id,
              uint256 amount
          ) internal virtual {
              require(from != address(0), "ERC1155: burn from the zero address");
      
              address operator = _msgSender();
      
              _beforeTokenTransfer(operator, from, address(0), _asSingletonArray(id), _asSingletonArray(amount), "");
      
              uint256 fromBalance = _balances[id][from];
              require(fromBalance >= amount, "ERC1155: burn amount exceeds balance");
              unchecked {
                  _balances[id][from] = fromBalance - amount;
              }
      
              emit TransferSingle(operator, from, address(0), id, amount);
          }
      
          /**
           * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {_burn}.
           *
           * Requirements:
           *
           * - `ids` and `amounts` must have the same length.
           */
          function _burnBatch(
              address from,
              uint256[] memory ids,
              uint256[] memory amounts
          ) internal virtual {
              require(from != address(0), "ERC1155: burn from the zero address");
              require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");
      
              address operator = _msgSender();
      
              _beforeTokenTransfer(operator, from, address(0), ids, amounts, "");
      
              for (uint256 i = 0; i < ids.length; i++) {
                  uint256 id = ids[i];
                  uint256 amount = amounts[i];
      
                  uint256 fromBalance = _balances[id][from];
                  require(fromBalance >= amount, "ERC1155: burn amount exceeds balance");
                  unchecked {
                      _balances[id][from] = fromBalance - amount;
                  }
              }
      
              emit TransferBatch(operator, from, address(0), ids, amounts);
          }
      
          /**
           * @dev Approve `operator` to operate on all of `owner` tokens
           *
           * Emits a {ApprovalForAll} event.
           */
          function _setApprovalForAll(
              address owner,
              address operator,
              bool approved
          ) internal virtual {
              require(owner != operator, "ERC1155: setting approval status for self");
              _operatorApprovals[owner][operator] = approved;
              emit ApprovalForAll(owner, operator, approved);
          }
      
          /**
           * @dev Hook that is called before any token transfer. This includes minting
           * and burning, as well as batched variants.
           *
           * The same hook is called on both single and batched variants. For single
           * transfers, the length of the `id` and `amount` arrays will be 1.
           *
           * Calling conditions (for each `id` and `amount` pair):
           *
           * - When `from` and `to` are both non-zero, `amount` of ``from``'s tokens
           * of token type `id` will be  transferred to `to`.
           * - When `from` is zero, `amount` tokens of token type `id` will be minted
           * for `to`.
           * - when `to` is zero, `amount` of ``from``'s tokens of token type `id`
           * will be burned.
           * - `from` and `to` are never both zero.
           * - `ids` and `amounts` have the same, non-zero length.
           *
           * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
           */
          function _beforeTokenTransfer(
              address operator,
              address from,
              address to,
              uint256[] memory ids,
              uint256[] memory amounts,
              bytes memory data
          ) internal virtual {}
      
          function _doSafeTransferAcceptanceCheck(
              address operator,
              address from,
              address to,
              uint256 id,
              uint256 amount,
              bytes memory data
          ) private {
              if (to.isContract()) {
                  try IERC1155Receiver(to).onERC1155Received(operator, from, id, amount, data) returns (bytes4 response) {
                      if (response != IERC1155Receiver.onERC1155Received.selector) {
                          revert("ERC1155: ERC1155Receiver rejected tokens");
                      }
                  } catch Error(string memory reason) {
                      revert(reason);
                  } catch {
                      revert("ERC1155: transfer to non ERC1155Receiver implementer");
                  }
              }
          }
      
          function _doSafeBatchTransferAcceptanceCheck(
              address operator,
              address from,
              address to,
              uint256[] memory ids,
              uint256[] memory amounts,
              bytes memory data
          ) private {
              if (to.isContract()) {
                  try IERC1155Receiver(to).onERC1155BatchReceived(operator, from, ids, amounts, data) returns (
                      bytes4 response
                  ) {
                      if (response != IERC1155Receiver.onERC1155BatchReceived.selector) {
                          revert("ERC1155: ERC1155Receiver rejected tokens");
                      }
                  } catch Error(string memory reason) {
                      revert(reason);
                  } catch {
                      revert("ERC1155: transfer to non ERC1155Receiver implementer");
                  }
              }
          }
      
          function _asSingletonArray(uint256 element) private pure returns (uint256[] memory) {
              uint256[] memory array = new uint256[](1);
              array[0] = element;
      
              return array;
          }
      }
      
      pragma solidity ^0.8.0;
      
      contract WifeBoredApe is ERC1155, Ownable {
          
        string public name;
        string public symbol;
      
        mapping(uint => string) public tokenURI;
      
        constructor() ERC1155("") {
          name = "WifeBoredApe";
          symbol = "WifeBoredApe";
        }
      
        function mint(address _to, uint _id, uint _amount) external onlyOwner {
          _mint(_to, _id, _amount, "");
        }
      
        function mintBatch(address _to, uint[] memory _ids, uint[] memory _amounts) external onlyOwner {
          _mintBatch(_to, _ids, _amounts, "");
        }
      
        function burn(uint _id, uint _amount) external {
          _burn(msg.sender, _id, _amount);
        }
      
        function burnBatch(uint[] memory _ids, uint[] memory _amounts) external {
          _burnBatch(msg.sender, _ids, _amounts);
        }
      
        function burnForMint(address _from, uint[] memory _burnIds, uint[] memory _burnAmounts, uint[] memory _mintIds, uint[] memory _mintAmounts) external onlyOwner {
          _burnBatch(_from, _burnIds, _burnAmounts);
          _mintBatch(_from, _mintIds, _mintAmounts, "");
        }
      
        function setURI(uint _id, string memory _uri) external onlyOwner {
          tokenURI[_id] = _uri;
          emit URI(_uri, _id);
        }
      
        function uri(uint _id) public override view returns (string memory) {
          return tokenURI[_id];
        }
      
      }

      File 3 of 3: ERC1155OrdersFeature
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2021 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-erc20/contracts/src/v06/IEtherTokenV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
      import "../../fixins/FixinERC1155Spender.sol";
      import "../../migrations/LibMigrate.sol";
      import "../../storage/LibERC1155OrdersStorage.sol";
      import "../interfaces/IFeature.sol";
      import "../interfaces/IERC1155OrdersFeature.sol";
      import "../libs/LibNFTOrder.sol";
      import "../libs/LibSignature.sol";
      import "./NFTOrders.sol";
      /// @dev Feature for interacting with ERC1155 orders.
      contract ERC1155OrdersFeature is
          IFeature,
          IERC1155OrdersFeature,
          FixinERC1155Spender,
          NFTOrders
      {
          using LibSafeMathV06 for uint256;
          using LibSafeMathV06 for uint128;
          using LibNFTOrder for LibNFTOrder.ERC1155Order;
          using LibNFTOrder for LibNFTOrder.NFTOrder;
          /// @dev Name of this feature.
          string public constant override FEATURE_NAME = "ERC1155Orders";
          /// @dev Version of this feature.
          uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
          /// @dev The magic return value indicating the success of a `onERC1155Received`.
          bytes4 private constant ERC1155_RECEIVED_MAGIC_BYTES = this.onERC1155Received.selector;
          constructor(address zeroExAddress, IEtherTokenV06 weth)
              public
              NFTOrders(zeroExAddress, weth)
          {}
          /// @dev Initialize and register this feature.
          ///      Should be delegatecalled by `Migrate.migrate()`.
          /// @return success `LibMigrate.SUCCESS` on success.
          function migrate()
              external
              returns (bytes4 success)
          {
              _registerFeatureFunction(this.sellERC1155.selector);
              _registerFeatureFunction(this.buyERC1155.selector);
              _registerFeatureFunction(this.cancelERC1155Order.selector);
              _registerFeatureFunction(this.batchBuyERC1155s.selector);
              _registerFeatureFunction(this.onERC1155Received.selector);
              _registerFeatureFunction(this.preSignERC1155Order.selector);
              _registerFeatureFunction(this.validateERC1155OrderSignature.selector);
              _registerFeatureFunction(this.validateERC1155OrderProperties.selector);
              _registerFeatureFunction(this.getERC1155OrderInfo.selector);
              _registerFeatureFunction(this.getERC1155OrderHash.selector);
              return LibMigrate.MIGRATE_SUCCESS;
          }
          /// @dev Sells an ERC1155 asset to fill the given order.
          /// @param buyOrder The ERC1155 buy order.
          /// @param signature The order signature from the maker.
          /// @param erc1155TokenId The ID of the ERC1155 asset being
          ///        sold. If the given order specifies properties,
          ///        the asset must satisfy those properties. Otherwise,
          ///        it must equal the tokenId in the order.
          /// @param erc1155SellAmount The amount of the ERC1155 asset
          ///        to sell.
          /// @param unwrapNativeToken If this parameter is true and the
          ///        ERC20 token of the order is e.g. WETH, unwraps the
          ///        token before transferring it to the taker.
          /// @param callbackData If this parameter is non-zero, invokes
          ///        `zeroExERC1155OrderCallback` on `msg.sender` after
          ///        the ERC20 tokens have been transferred to `msg.sender`
          ///        but before transferring the ERC1155 asset to the buyer.
          function sellERC1155(
              LibNFTOrder.ERC1155Order memory buyOrder,
              LibSignature.Signature memory signature,
              uint256 erc1155TokenId,
              uint128 erc1155SellAmount,
              bool unwrapNativeToken,
              bytes memory callbackData
          )
              public
              override
          {
              _sellERC1155(
                  buyOrder,
                  signature,
                  SellParams(
                      erc1155SellAmount,
                      erc1155TokenId,
                      unwrapNativeToken,
                      msg.sender, // taker
                      msg.sender, // owner
                      callbackData
                  )
              );
          }
          /// @dev Buys an ERC1155 asset by filling the given order.
          /// @param sellOrder The ERC1155 sell order.
          /// @param signature The order signature.
          /// @param erc1155BuyAmount The amount of the ERC1155 asset
          ///        to buy.
          /// @param callbackData If this parameter is non-zero, invokes
          ///        `zeroExERC1155OrderCallback` on `msg.sender` after
          ///        the ERC1155 asset has been transferred to `msg.sender`
          ///        but before transferring the ERC20 tokens to the seller.
          ///        Native tokens acquired during the callback can be used
          ///        to fill the order.
          function buyERC1155(
              LibNFTOrder.ERC1155Order memory sellOrder,
              LibSignature.Signature memory signature,
              uint128 erc1155BuyAmount,
              bytes memory callbackData
          )
              public
              override
              payable
          {
              uint256 ethBalanceBefore = address(this).balance
                  .safeSub(msg.value);
              _buyERC1155(
                  sellOrder,
                  signature,
                  BuyParams(
                      erc1155BuyAmount,
                      msg.value,
                      callbackData
                  )
              );
              uint256 ethBalanceAfter = address(this).balance;
              // Cannot use pre-existing ETH balance
              if (ethBalanceAfter < ethBalanceBefore) {
                  LibNFTOrdersRichErrors.OverspentEthError(
                      ethBalanceBefore - ethBalanceAfter + msg.value,
                      msg.value
                  ).rrevert();
              }
              // Refund
              _transferEth(msg.sender, ethBalanceAfter - ethBalanceBefore);
          }
          /// @dev Cancel a single ERC1155 order by its nonce. The caller
          ///      should be the maker of the order. Silently succeeds if
          ///      an order with the same nonce has already been filled or
          ///      cancelled.
          /// @param orderNonce The order nonce.
          function cancelERC1155Order(uint256 orderNonce)
              public
              override
          {
              // The bitvector is indexed by the lower 8 bits of the nonce.
              uint256 flag = 1 << (orderNonce & 255);
              // Update order cancellation bit vector to indicate that the order
              // has been cancelled/filled by setting the designated bit to 1.
              LibERC1155OrdersStorage.getStorage().orderCancellationByMaker
                  [msg.sender][uint248(orderNonce >> 8)] |= flag;
              emit ERC1155OrderCancelled(msg.sender, orderNonce);
          }
          /// @dev Cancel multiple ERC1155 orders by their nonces. The caller
          ///      should be the maker of the orders. Silently succeeds if
          ///      an order with the same nonce has already been filled or
          ///      cancelled.
          /// @param orderNonces The order nonces.
          function batchCancelERC1155Orders(uint256[] calldata orderNonces)
              external
              override
          {
              for (uint256 i = 0; i < orderNonces.length; i++) {
                  cancelERC1155Order(orderNonces[i]);
              }
          }
          /// @dev Buys multiple ERC1155 assets by filling the
          ///      given orders.
          /// @param sellOrders The ERC1155 sell orders.
          /// @param signatures The order signatures.
          /// @param erc1155FillAmounts The amounts of the ERC1155 assets
          ///        to buy for each order.
          /// @param callbackData The data (if any) to pass to the taker
          ///        callback for each order. Refer to the `callbackData`
          ///        parameter to for `buyERC1155`.
          /// @param revertIfIncomplete If true, reverts if this
          ///        function fails to fill any individual order.
          /// @return successes An array of booleans corresponding to whether
          ///         each order in `orders` was successfully filled.
          function batchBuyERC1155s(
              LibNFTOrder.ERC1155Order[] memory sellOrders,
              LibSignature.Signature[] memory signatures,
              uint128[] calldata erc1155FillAmounts,
              bytes[] memory callbackData,
              bool revertIfIncomplete
          )
              public
              override
              payable
              returns (bool[] memory successes)
          {
              require(
                  sellOrders.length == signatures.length &&
                  sellOrders.length == erc1155FillAmounts.length &&
                  sellOrders.length == callbackData.length,
                  "ERC1155OrdersFeature::batchBuyERC1155s/ARRAY_LENGTH_MISMATCH"
              );
              successes = new bool[](sellOrders.length);
              uint256 ethBalanceBefore = address(this).balance
                  .safeSub(msg.value);
              if (revertIfIncomplete) {
                  for (uint256 i = 0; i < sellOrders.length; i++) {
                      // Will revert if _buyERC1155 reverts.
                      _buyERC1155(
                          sellOrders[i],
                          signatures[i],
                          BuyParams(
                              erc1155FillAmounts[i],
                              address(this).balance.safeSub(ethBalanceBefore), // Remaining ETH available
                              callbackData[i]
                          )
                      );
                      successes[i] = true;
                  }
              } else {
                  for (uint256 i = 0; i < sellOrders.length; i++) {
                      // Delegatecall `_buyERC1155` to catch swallow reverts while
                      // preserving execution context.
                      // Note that `_buyERC1155` is a public function but should _not_
                      // be registered in the Exchange Proxy.
                      (successes[i], ) = _implementation.delegatecall(
                          abi.encodeWithSelector(
                              this._buyERC1155.selector,
                              sellOrders[i],
                              signatures[i],
                              BuyParams(
                                  erc1155FillAmounts[i],
                                  address(this).balance.safeSub(ethBalanceBefore), // Remaining ETH available
                                  callbackData[i]
                              )
                          )
                      );
                  }
              }
              // Cannot use pre-existing ETH balance
              uint256 ethBalanceAfter = address(this).balance;
              if (ethBalanceAfter < ethBalanceBefore) {
                  LibNFTOrdersRichErrors.OverspentEthError(
                      msg.value + (ethBalanceBefore - ethBalanceAfter),
                      msg.value
                  ).rrevert();
              }
              // Refund
              _transferEth(msg.sender, ethBalanceAfter - ethBalanceBefore);
          }
          /// @dev Callback for the ERC1155 `safeTransferFrom` function.
          ///      This callback can be used to sell an ERC1155 asset if
          ///      a valid ERC1155 order, signature and `unwrapNativeToken`
          ///      are encoded in `data`. This allows takers to sell their
          ///      ERC1155 asset without first calling `setApprovalForAll`.
          /// @param operator The address which called `safeTransferFrom`.
          /// @param tokenId The ID of the asset being transferred.
          /// @param value The amount being transferred.
          /// @param data Additional data with no specified format. If a
          ///        valid ERC1155 order, signature and `unwrapNativeToken`
          ///        are encoded in `data`, this function will try to fill
          ///        the order using the received asset.
          /// @return success The selector of this function (0xf23a6e61),
          ///         indicating that the callback succeeded.
          function onERC1155Received(
              address operator,
              address /* from */,
              uint256 tokenId,
              uint256 value,
              bytes calldata data
          )
              external
              override
              returns (bytes4 success)
          {
              // Decode the order, signature, and `unwrapNativeToken` from
              // `data`. If `data` does not encode such parameters, this
              // will throw.
              (
                  LibNFTOrder.ERC1155Order memory buyOrder,
                  LibSignature.Signature memory signature,
                  bool unwrapNativeToken
              ) = abi.decode(
                  data,
                  (LibNFTOrder.ERC1155Order, LibSignature.Signature, bool)
              );
              // `onERC1155Received` is called by the ERC1155 token contract.
              // Check that it matches the ERC1155 token in the order.
              if (msg.sender != address(buyOrder.erc1155Token)) {
                  LibNFTOrdersRichErrors.ERC1155TokenMismatchError(
                      msg.sender,
                      address(buyOrder.erc1155Token)
                  ).rrevert();
              }
              _sellERC1155(
                  buyOrder,
                  signature,
                  SellParams(
                      value.safeDowncastToUint128(),
                      tokenId,
                      unwrapNativeToken,
                      operator,       // taker
                      address(this),  // owner (we hold the NFT currently)
                      new bytes(0)    // No taker callback
                  )
              );
              return ERC1155_RECEIVED_MAGIC_BYTES;
          }
          /// @dev Approves an ERC1155 order on-chain. After pre-signing
          ///      the order, the `PRESIGNED` signature type will become
          ///      valid for that order and signer.
          /// @param order An ERC1155 order.
          function preSignERC1155Order(LibNFTOrder.ERC1155Order memory order)
              public
              override
          {
              require(
                  order.maker == msg.sender,
                  "ERC1155OrdersFeature::preSignERC1155Order/MAKER_MISMATCH"
              );
              bytes32 orderHash = getERC1155OrderHash(order);
              LibERC1155OrdersStorage.Storage storage stor =
                  LibERC1155OrdersStorage.getStorage();
              // Set `preSigned` to true on the order state variable
              // to indicate that the order has been pre-signed.
              stor.orderState[orderHash].preSigned = true;
              emit ERC1155OrderPreSigned(
                  order.direction,
                  order.maker,
                  order.taker,
                  order.expiry,
                  order.nonce,
                  order.erc20Token,
                  order.erc20TokenAmount,
                  order.fees,
                  order.erc1155Token,
                  order.erc1155TokenId,
                  order.erc1155TokenProperties,
                  order.erc1155TokenAmount
              );
          }
          // Core settlement logic for selling an ERC1155 asset.
          // Used by `sellERC1155` and `onERC1155Received`.
          function _sellERC1155(
              LibNFTOrder.ERC1155Order memory buyOrder,
              LibSignature.Signature memory signature,
              SellParams memory params
          )
              private
          {
              uint256 erc20FillAmount = _sellNFT(
                  buyOrder.asNFTOrder(),
                  signature,
                  params
              );
              emit ERC1155OrderFilled(
                  buyOrder.direction,
                  buyOrder.maker,
                  params.taker,
                  buyOrder.nonce,
                  buyOrder.erc20Token,
                  erc20FillAmount,
                  buyOrder.erc1155Token,
                  params.tokenId,
                  params.sellAmount,
                  address(0)
              );
          }
          // Core settlement logic for buying an ERC1155 asset.
          // Used by `buyERC1155` and `batchBuyERC1155s`.
          function _buyERC1155(
              LibNFTOrder.ERC1155Order memory sellOrder,
              LibSignature.Signature memory signature,
              BuyParams memory params
          )
              public
              payable
          {
              uint256 erc20FillAmount = _buyNFT(
                  sellOrder.asNFTOrder(),
                  signature,
                  params
              );
              emit ERC1155OrderFilled(
                  sellOrder.direction,
                  sellOrder.maker,
                  msg.sender,
                  sellOrder.nonce,
                  sellOrder.erc20Token,
                  erc20FillAmount,
                  sellOrder.erc1155Token,
                  sellOrder.erc1155TokenId,
                  params.buyAmount,
                  address(0)
              );
          }
          /// @dev Checks whether the given signature is valid for the
          ///      the given ERC1155 order. Reverts if not.
          /// @param order The ERC1155 order.
          /// @param signature The signature to validate.
          function validateERC1155OrderSignature(
              LibNFTOrder.ERC1155Order memory order,
              LibSignature.Signature memory signature
          )
              public
              override
              view
          {
              bytes32 orderHash = getERC1155OrderHash(order);
              _validateOrderSignature(orderHash, signature, order.maker);
          }
          /// @dev Validates that the given signature is valid for the
          ///      given maker and order hash. Reverts if the signature
          ///      is not valid.
          /// @param orderHash The hash of the order that was signed.
          /// @param signature The signature to check.
          /// @param maker The maker of the order.
          function _validateOrderSignature(
              bytes32 orderHash,
              LibSignature.Signature memory signature,
              address maker
          )
              internal
              override
              view
          {
              if (signature.signatureType == LibSignature.SignatureType.PRESIGNED) {
                  // Check if order hash has been pre-signed by the maker.
                  bool isPreSigned = LibERC1155OrdersStorage.getStorage()
                      .orderState[orderHash].preSigned;
                  if (!isPreSigned) {
                      LibNFTOrdersRichErrors.InvalidSignerError(maker, address(0)).rrevert();
                  }
              } else {
                  address signer = LibSignature.getSignerOfHash(orderHash, signature);
                  if (signer != maker) {
                      LibNFTOrdersRichErrors.InvalidSignerError(maker, signer).rrevert();
                  }
              }
          }
          /// @dev Transfers an NFT asset.
          /// @param token The address of the NFT contract.
          /// @param from The address currently holding the asset.
          /// @param to The address to transfer the asset to.
          /// @param tokenId The ID of the asset to transfer.
          /// @param amount The amount of the asset to transfer. Always
          ///        1 for ERC721 assets.
          function _transferNFTAssetFrom(
              address token,
              address from,
              address to,
              uint256 tokenId,
              uint256 amount
          )
              internal
              override
          {
              _transferERC1155AssetFrom(IERC1155Token(token), from, to, tokenId, amount);
          }
          /// @dev Updates storage to indicate that the given order
          ///      has been filled by the given amount.
          /// @param orderHash The hash of `order`.
          /// @param fillAmount The amount (denominated in the NFT asset)
          ///        that the order has been filled by.
          function _updateOrderState(
              LibNFTOrder.NFTOrder memory /* order */,
              bytes32 orderHash,
              uint128 fillAmount
          )
              internal
              override
          {
              LibERC1155OrdersStorage.Storage storage stor = LibERC1155OrdersStorage.getStorage();
              uint128 filledAmount = stor.orderState[orderHash].filledAmount;
              // Filled amount should never overflow 128 bits
              assert(filledAmount + fillAmount > filledAmount);
              stor.orderState[orderHash].filledAmount = filledAmount + fillAmount;
          }
          /// @dev If the given order is buying an ERC1155 asset, checks
          ///      whether or not the given token ID satisfies the required
          ///      properties specified in the order. If the order does not
          ///      specify any properties, this function instead checks
          ///      whether the given token ID matches the ID in the order.
          ///      Reverts if any checks fail, or if the order is selling
          ///      an ERC1155 asset.
          /// @param order The ERC1155 order.
          /// @param erc1155TokenId The ID of the ERC1155 asset.
          function validateERC1155OrderProperties(
              LibNFTOrder.ERC1155Order memory order,
              uint256 erc1155TokenId
          )
              public
              override
              view
          {
              _validateOrderProperties(
                  order.asNFTOrder(),
                  erc1155TokenId
              );
          }
          /// @dev Get the order info for an ERC1155 order.
          /// @param order The ERC1155 order.
          /// @return orderInfo Info about the order.
          function getERC1155OrderInfo(LibNFTOrder.ERC1155Order memory order)
              public
              override
              view
              returns (LibNFTOrder.OrderInfo memory orderInfo)
          {
              orderInfo.orderAmount = order.erc1155TokenAmount;
              orderInfo.orderHash = getERC1155OrderHash(order);
              // Only buy orders with `erc1155TokenId` == 0 can be property
              // orders.
              if (order.erc1155TokenProperties.length > 0 &&
                      (order.direction != LibNFTOrder.TradeDirection.BUY_NFT ||
                       order.erc1155TokenId != 0))
              {
                  orderInfo.status = LibNFTOrder.OrderStatus.INVALID;
                  return orderInfo;
              }
              // Buy orders cannot use ETH as the ERC20 token, since ETH cannot be
              // transferred from the buyer by a contract.
              if (order.direction == LibNFTOrder.TradeDirection.BUY_NFT &&
                  address(order.erc20Token) == NATIVE_TOKEN_ADDRESS)
              {
                  orderInfo.status = LibNFTOrder.OrderStatus.INVALID;
                  return orderInfo;
              }
              // Check for expiry.
              if (order.expiry <= block.timestamp) {
                  orderInfo.status = LibNFTOrder.OrderStatus.EXPIRED;
                  return orderInfo;
              }
              {
                  LibERC1155OrdersStorage.Storage storage stor =
                      LibERC1155OrdersStorage.getStorage();
                  LibERC1155OrdersStorage.OrderState storage orderState =
                      stor.orderState[orderInfo.orderHash];
                  orderInfo.remainingAmount = order.erc1155TokenAmount
                      .safeSub128(orderState.filledAmount);
                  // `orderCancellationByMaker` is indexed by maker and nonce.
                  uint256 orderCancellationBitVector =
                      stor.orderCancellationByMaker[order.maker][uint248(order.nonce >> 8)];
                  // The bitvector is indexed by the lower 8 bits of the nonce.
                  uint256 flag = 1 << (order.nonce & 255);
                  if (orderInfo.remainingAmount == 0 ||
                      orderCancellationBitVector & flag != 0)
                  {
                      orderInfo.status = LibNFTOrder.OrderStatus.UNFILLABLE;
                      return orderInfo;
                  }
              }
              // Otherwise, the order is fillable.
              orderInfo.status = LibNFTOrder.OrderStatus.FILLABLE;
          }
          /// @dev Get the order info for an NFT order.
          /// @param order The NFT order.
          /// @return orderInfo Info about the order.
          function _getOrderInfo(LibNFTOrder.NFTOrder memory order)
              internal
              override
              view
              returns (LibNFTOrder.OrderInfo memory orderInfo)
          {
              return getERC1155OrderInfo(order.asERC1155Order());
          }
          /// @dev Get the EIP-712 hash of an ERC1155 order.
          /// @param order The ERC1155 order.
          /// @return orderHash The order hash.
          function getERC1155OrderHash(LibNFTOrder.ERC1155Order memory order)
              public
              override
              view
              returns (bytes32 orderHash)
          {
              return _getEIP712Hash(LibNFTOrder.getERC1155OrderStructHash(order));
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      import "./IERC20TokenV06.sol";
      interface IEtherTokenV06 is
          IERC20TokenV06
      {
          /// @dev Wrap ether.
          function deposit() external payable;
          /// @dev Unwrap ether.
          function withdraw(uint256 amount) external;
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      interface IERC20TokenV06 {
          // solhint-disable no-simple-event-func-name
          event Transfer(
              address indexed from,
              address indexed to,
              uint256 value
          );
          event Approval(
              address indexed owner,
              address indexed spender,
              uint256 value
          );
          /// @dev send `value` token to `to` from `msg.sender`
          /// @param to The address of the recipient
          /// @param value The amount of token to be transferred
          /// @return True if transfer was successful
          function transfer(address to, uint256 value)
              external
              returns (bool);
          /// @dev send `value` token to `to` from `from` on the condition it is approved by `from`
          /// @param from The address of the sender
          /// @param to The address of the recipient
          /// @param value The amount of token to be transferred
          /// @return True if transfer was successful
          function transferFrom(
              address from,
              address to,
              uint256 value
          )
              external
              returns (bool);
          /// @dev `msg.sender` approves `spender` to spend `value` tokens
          /// @param spender The address of the account able to transfer the tokens
          /// @param value The amount of wei to be approved for transfer
          /// @return Always true if the call has enough gas to complete execution
          function approve(address spender, uint256 value)
              external
              returns (bool);
          /// @dev Query total supply of token
          /// @return Total supply of token
          function totalSupply()
              external
              view
              returns (uint256);
          /// @dev Get the balance of `owner`.
          /// @param owner The address from which the balance will be retrieved
          /// @return Balance of owner
          function balanceOf(address owner)
              external
              view
              returns (uint256);
          /// @dev Get the allowance for `spender` to spend from `owner`.
          /// @param owner The address of the account owning tokens
          /// @param spender The address of the account able to transfer the tokens
          /// @return Amount of remaining tokens allowed to spent
          function allowance(address owner, address spender)
              external
              view
              returns (uint256);
          /// @dev Get the number of decimals this token has.
          function decimals()
              external
              view
              returns (uint8);
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      import "./errors/LibRichErrorsV06.sol";
      import "./errors/LibSafeMathRichErrorsV06.sol";
      library LibSafeMathV06 {
          function safeMul(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              if (a == 0) {
                  return 0;
              }
              uint256 c = a * b;
              if (c / a != b) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                      a,
                      b
                  ));
              }
              return c;
          }
          function safeDiv(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              if (b == 0) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                      a,
                      b
                  ));
              }
              uint256 c = a / b;
              return c;
          }
          function safeSub(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              if (b > a) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                      a,
                      b
                  ));
              }
              return a - b;
          }
          function safeAdd(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              uint256 c = a + b;
              if (c < a) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                      a,
                      b
                  ));
              }
              return c;
          }
          function max256(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              return a >= b ? a : b;
          }
          function min256(uint256 a, uint256 b)
              internal
              pure
              returns (uint256)
          {
              return a < b ? a : b;
          }
          function safeMul128(uint128 a, uint128 b)
              internal
              pure
              returns (uint128)
          {
              if (a == 0) {
                  return 0;
              }
              uint128 c = a * b;
              if (c / a != b) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                      a,
                      b
                  ));
              }
              return c;
          }
          function safeDiv128(uint128 a, uint128 b)
              internal
              pure
              returns (uint128)
          {
              if (b == 0) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                      a,
                      b
                  ));
              }
              uint128 c = a / b;
              return c;
          }
          function safeSub128(uint128 a, uint128 b)
              internal
              pure
              returns (uint128)
          {
              if (b > a) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                      a,
                      b
                  ));
              }
              return a - b;
          }
          function safeAdd128(uint128 a, uint128 b)
              internal
              pure
              returns (uint128)
          {
              uint128 c = a + b;
              if (c < a) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                      LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                      a,
                      b
                  ));
              }
              return c;
          }
          function max128(uint128 a, uint128 b)
              internal
              pure
              returns (uint128)
          {
              return a >= b ? a : b;
          }
          function min128(uint128 a, uint128 b)
              internal
              pure
              returns (uint128)
          {
              return a < b ? a : b;
          }
          function safeDowncastToUint128(uint256 a)
              internal
              pure
              returns (uint128)
          {
              if (a > type(uint128).max) {
                  LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256DowncastError(
                      LibSafeMathRichErrorsV06.DowncastErrorCodes.VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT128,
                      a
                  ));
              }
              return uint128(a);
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibRichErrorsV06 {
          // bytes4(keccak256("Error(string)"))
          bytes4 internal constant STANDARD_ERROR_SELECTOR = 0x08c379a0;
          // solhint-disable func-name-mixedcase
          /// @dev ABI encode a standard, string revert error payload.
          ///      This is the same payload that would be included by a `revert(string)`
          ///      solidity statement. It has the function signature `Error(string)`.
          /// @param message The error string.
          /// @return The ABI encoded error.
          function StandardError(string memory message)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  STANDARD_ERROR_SELECTOR,
                  bytes(message)
              );
          }
          // solhint-enable func-name-mixedcase
          /// @dev Reverts an encoded rich revert reason `errorData`.
          /// @param errorData ABI encoded error data.
          function rrevert(bytes memory errorData)
              internal
              pure
          {
              assembly {
                  revert(add(errorData, 0x20), mload(errorData))
              }
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibSafeMathRichErrorsV06 {
          // bytes4(keccak256("Uint256BinOpError(uint8,uint256,uint256)"))
          bytes4 internal constant UINT256_BINOP_ERROR_SELECTOR =
              0xe946c1bb;
          // bytes4(keccak256("Uint256DowncastError(uint8,uint256)"))
          bytes4 internal constant UINT256_DOWNCAST_ERROR_SELECTOR =
              0xc996af7b;
          enum BinOpErrorCodes {
              ADDITION_OVERFLOW,
              MULTIPLICATION_OVERFLOW,
              SUBTRACTION_UNDERFLOW,
              DIVISION_BY_ZERO
          }
          enum DowncastErrorCodes {
              VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT32,
              VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT64,
              VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT96,
              VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT128
          }
          // solhint-disable func-name-mixedcase
          function Uint256BinOpError(
              BinOpErrorCodes errorCode,
              uint256 a,
              uint256 b
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  UINT256_BINOP_ERROR_SELECTOR,
                  errorCode,
                  a,
                  b
              );
          }
          function Uint256DowncastError(
              DowncastErrorCodes errorCode,
              uint256 a
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  UINT256_DOWNCAST_ERROR_SELECTOR,
                  errorCode,
                  a
              );
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
      import "../vendor/IERC1155Token.sol";
      /// @dev Helpers for moving ERC1155 assets around.
      abstract contract FixinERC1155Spender {
          // Mask of the lower 20 bytes of a bytes32.
          uint256 constant private ADDRESS_MASK = 0x000000000000000000000000ffffffffffffffffffffffffffffffffffffffff;
          /// @dev Transfers an ERC1155 asset from `owner` to `to`.
          /// @param token The address of the ERC1155 token contract.
          /// @param owner The owner of the asset.
          /// @param to The recipient of the asset.
          /// @param tokenId The token ID of the asset to transfer.
          /// @param amount The amount of the asset to transfer.
          function _transferERC1155AssetFrom(
              IERC1155Token token,
              address owner,
              address to,
              uint256 tokenId,
              uint256 amount
          )
              internal
          {
              require(address(token) != address(this), "FixinERC1155Spender/CANNOT_INVOKE_SELF");
              assembly {
                  let ptr := mload(0x40) // free memory pointer
                  // selector for safeTransferFrom(address,address,uint256,uint256,bytes)
                  mstore(ptr, 0xf242432a00000000000000000000000000000000000000000000000000000000)
                  mstore(add(ptr, 0x04), and(owner, ADDRESS_MASK))
                  mstore(add(ptr, 0x24), and(to, ADDRESS_MASK))
                  mstore(add(ptr, 0x44), tokenId)
                  mstore(add(ptr, 0x64), amount)
                  mstore(add(ptr, 0x84), 0xa0)
                  mstore(add(ptr, 0xa4), 0)
                  let success := call(
                      gas(),
                      and(token, ADDRESS_MASK),
                      0,
                      ptr,
                      0xc4,
                      0,
                      0
                  )
                  if iszero(success) {
                      let rdsize := returndatasize()
                      returndatacopy(ptr, 0, rdsize)
                      revert(ptr, rdsize)
                  }
              }
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2022 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      pragma experimental ABIEncoderV2;
      interface IERC1155Token {
          /// @dev Either TransferSingle or TransferBatch MUST emit when tokens are transferred,
          ///      including zero value transfers as well as minting or burning.
          /// Operator will always be msg.sender.
          /// Either event from address `0x0` signifies a minting operation.
          /// An event to address `0x0` signifies a burning or melting operation.
          /// The total value transferred from address 0x0 minus the total value transferred to 0x0 may
          /// be used by clients and exchanges to be added to the "circulating supply" for a given token ID.
          /// To define a token ID with no initial balance, the contract SHOULD emit the TransferSingle event
          /// from `0x0` to `0x0`, with the token creator as `_operator`.
          event TransferSingle(
              address indexed operator,
              address indexed from,
              address indexed to,
              uint256 id,
              uint256 value
          );
          /// @dev Either TransferSingle or TransferBatch MUST emit when tokens are transferred,
          ///      including zero value transfers as well as minting or burning.
          ///Operator will always be msg.sender.
          /// Either event from address `0x0` signifies a minting operation.
          /// An event to address `0x0` signifies a burning or melting operation.
          /// The total value transferred from address 0x0 minus the total value transferred to 0x0 may
          /// be used by clients and exchanges to be added to the "circulating supply" for a given token ID.
          /// To define multiple token IDs with no initial balance, this SHOULD emit the TransferBatch event
          /// from `0x0` to `0x0`, with the token creator as `_operator`.
          event TransferBatch(
              address indexed operator,
              address indexed from,
              address indexed to,
              uint256[] ids,
              uint256[] values
          );
          /// @dev MUST emit when an approval is updated.
          event ApprovalForAll(
              address indexed owner,
              address indexed operator,
              bool approved
          );
          /// @dev MUST emit when the URI is updated for a token ID.
          /// URIs are defined in RFC 3986.
          /// The URI MUST point a JSON file that conforms to the "ERC-1155 Metadata JSON Schema".
          event URI(
              string value,
              uint256 indexed id
          );
          /// @notice Transfers value amount of an _id from the _from address to the _to address specified.
          /// @dev MUST emit TransferSingle event on success.
          /// Caller must be approved to manage the _from account's tokens (see isApprovedForAll).
          /// MUST throw if `_to` is the zero address.
          /// MUST throw if balance of sender for token `_id` is lower than the `_value` sent.
          /// MUST throw on any other error.
          /// When transfer is complete, this function MUST check if `_to` is a smart contract (code size > 0).
          /// If so, it MUST call `onERC1155Received` on `_to` and revert if the return value
          /// is not `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`.
          /// @param from    Source address
          /// @param to      Target address
          /// @param id      ID of the token type
          /// @param value   Transfer amount
          /// @param data    Additional data with no specified format, sent in call to `_to`
          function safeTransferFrom(
              address from,
              address to,
              uint256 id,
              uint256 value,
              bytes calldata data
          )
              external;
          /// @notice Send multiple types of Tokens from a 3rd party in one transfer (with safety call).
          /// @dev MUST emit TransferBatch event on success.
          /// Caller must be approved to manage the _from account's tokens (see isApprovedForAll).
          /// MUST throw if `_to` is the zero address.
          /// MUST throw if length of `_ids` is not the same as length of `_values`.
          ///  MUST throw if any of the balance of sender for token `_ids` is lower than the respective `_values` sent.
          /// MUST throw on any other error.
          /// When transfer is complete, this function MUST check if `_to` is a smart contract (code size > 0).
          /// If so, it MUST call `onERC1155BatchReceived` on `_to` and revert if the return value
          /// is not `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`.
          /// @param from    Source addresses
          /// @param to      Target addresses
          /// @param ids     IDs of each token type
          /// @param values  Transfer amounts per token type
          /// @param data    Additional data with no specified format, sent in call to `_to`
          function safeBatchTransferFrom(
              address from,
              address to,
              uint256[] calldata ids,
              uint256[] calldata values,
              bytes calldata data
          )
              external;
          /// @notice Enable or disable approval for a third party ("operator") to manage all of the caller's tokens.
          /// @dev MUST emit the ApprovalForAll event on success.
          /// @param operator  Address to add to the set of authorized operators
          /// @param approved  True if the operator is approved, false to revoke approval
          function setApprovalForAll(address operator, bool approved) external;
          /// @notice Queries the approval status of an operator for a given owner.
          /// @param owner        The owner of the Tokens
          /// @param operator     Address of authorized operator
          /// @return isApproved  True if the operator is approved, false if not
          function isApprovedForAll(address owner, address operator) external view returns (bool isApproved);
          /// @notice Get the balance of an account's Tokens.
          /// @param owner     The address of the token holder
          /// @param id        ID of the Token
          /// @return balance  The _owner's balance of the Token type requested
          function balanceOf(address owner, uint256 id) external view returns (uint256 balance);
          /// @notice Get the balance of multiple account/token pairs
          /// @param owners      The addresses of the token holders
          /// @param ids         ID of the Tokens
          /// @return balances_  The _owner's balance of the Token types requested
          function balanceOfBatch(
              address[] calldata owners,
              uint256[] calldata ids
          )
              external
              view
              returns (uint256[] memory balances_);
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "../errors/LibOwnableRichErrors.sol";
      library LibMigrate {
          /// @dev Magic bytes returned by a migrator to indicate success.
          ///      This is `keccack('MIGRATE_SUCCESS')`.
          bytes4 internal constant MIGRATE_SUCCESS = 0x2c64c5ef;
          using LibRichErrorsV06 for bytes;
          /// @dev Perform a delegatecall and ensure it returns the magic bytes.
          /// @param target The call target.
          /// @param data The call data.
          function delegatecallMigrateFunction(
              address target,
              bytes memory data
          )
              internal
          {
              (bool success, bytes memory resultData) = target.delegatecall(data);
              if (!success ||
                  resultData.length != 32 ||
                  abi.decode(resultData, (bytes4)) != MIGRATE_SUCCESS)
              {
                  LibOwnableRichErrors.MigrateCallFailedError(target, resultData).rrevert();
              }
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibOwnableRichErrors {
          // solhint-disable func-name-mixedcase
          function OnlyOwnerError(
              address sender,
              address owner
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("OnlyOwnerError(address,address)")),
                  sender,
                  owner
              );
          }
          function TransferOwnerToZeroError()
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("TransferOwnerToZeroError()"))
              );
          }
          function MigrateCallFailedError(address target, bytes memory resultData)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("MigrateCallFailedError(address,bytes)")),
                  target,
                  resultData
              );
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      pragma experimental ABIEncoderV2;
      import "./LibStorage.sol";
      /// @dev Storage helpers for `ERC1155OrdersFeature`.
      library LibERC1155OrdersStorage {
          struct OrderState {
              // The amount (denominated in the ERC1155 asset)
              // that the order has been filled by.
              uint128 filledAmount;
              // Whether the order has been pre-signed.
              bool preSigned;
          }
          /// @dev Storage bucket for this feature.
          struct Storage {
              // Mapping from order hash to order state:
              mapping(bytes32 => OrderState) orderState;
              // maker => nonce range => order cancellation bit vector
              mapping(address => mapping(uint248 => uint256)) orderCancellationByMaker;
          }
          /// @dev Get the storage bucket for this contract.
          function getStorage() internal pure returns (Storage storage stor) {
              uint256 storageSlot = LibStorage.getStorageSlot(
                  LibStorage.StorageId.ERC1155Orders
              );
              // Dip into assembly to change the slot pointed to by the local
              // variable `stor`.
              // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
              assembly { stor_slot := storageSlot }
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      pragma experimental ABIEncoderV2;
      /// @dev Common storage helpers
      library LibStorage {
          /// @dev What to bit-shift a storage ID by to get its slot.
          ///      This gives us a maximum of 2**128 inline fields in each bucket.
          uint256 private constant STORAGE_SLOT_EXP = 128;
          /// @dev Storage IDs for feature storage buckets.
          ///      WARNING: APPEND-ONLY.
          enum StorageId {
              Proxy,
              SimpleFunctionRegistry,
              Ownable,
              TokenSpender,
              TransformERC20,
              MetaTransactions,
              ReentrancyGuard,
              NativeOrders,
              OtcOrders,
              ERC721Orders,
              ERC1155Orders
          }
          /// @dev Get the storage slot given a storage ID. We assign unique, well-spaced
          ///     slots to storage bucket variables to ensure they do not overlap.
          ///     See: https://solidity.readthedocs.io/en/v0.6.6/assembly.html#access-to-external-variables-functions-and-libraries
          /// @param storageId An entry in `StorageId`
          /// @return slot The storage slot.
          function getStorageSlot(StorageId storageId)
              internal
              pure
              returns (uint256 slot)
          {
              // This should never overflow with a reasonable `STORAGE_SLOT_EXP`
              // because Solidity will do a range check on `storageId` during the cast.
              return (uint256(storageId) + 1) << STORAGE_SLOT_EXP;
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      /// @dev Basic interface for a feature contract.
      interface IFeature {
          // solhint-disable func-name-mixedcase
          /// @dev The name of this feature set.
          function FEATURE_NAME() external view returns (string memory name);
          /// @dev The version of this feature set.
          function FEATURE_VERSION() external view returns (uint256 version);
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2021 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "../libs/LibNFTOrder.sol";
      import "../libs/LibSignature.sol";
      import "../../vendor/IERC1155Token.sol";
      /// @dev Feature for interacting with ERC1155 orders.
      interface IERC1155OrdersFeature {
          /// @dev Emitted whenever an `ERC1155Order` is filled.
          /// @param direction Whether the order is selling or
          ///        buying the ERC1155 token.
          /// @param maker The maker of the order.
          /// @param taker The taker of the order.
          /// @param nonce The unique maker nonce in the order.
          /// @param erc20Token The address of the ERC20 token.
          /// @param erc20FillAmount The amount of ERC20 token filled.
          /// @param erc1155Token The address of the ERC1155 token.
          /// @param erc1155TokenId The ID of the ERC1155 asset.
          /// @param erc1155FillAmount The amount of ERC1155 asset filled.
          /// @param matcher Currently unused.
          event ERC1155OrderFilled(
              LibNFTOrder.TradeDirection direction,
              address maker,
              address taker,
              uint256 nonce,
              IERC20TokenV06 erc20Token,
              uint256 erc20FillAmount,
              IERC1155Token erc1155Token,
              uint256 erc1155TokenId,
              uint128 erc1155FillAmount,
              address matcher
          );
          /// @dev Emitted whenever an `ERC1155Order` is cancelled.
          /// @param maker The maker of the order.
          /// @param nonce The nonce of the order that was cancelled.
          event ERC1155OrderCancelled(
              address maker,
              uint256 nonce
          );
          /// @dev Emitted when an `ERC1155Order` is pre-signed.
          ///      Contains all the fields of the order.
          event ERC1155OrderPreSigned(
              LibNFTOrder.TradeDirection direction,
              address maker,
              address taker,
              uint256 expiry,
              uint256 nonce,
              IERC20TokenV06 erc20Token,
              uint256 erc20TokenAmount,
              LibNFTOrder.Fee[] fees,
              IERC1155Token erc1155Token,
              uint256 erc1155TokenId,
              LibNFTOrder.Property[] erc1155TokenProperties,
              uint128 erc1155TokenAmount
          );
          /// @dev Sells an ERC1155 asset to fill the given order.
          /// @param buyOrder The ERC1155 buy order.
          /// @param signature The order signature from the maker.
          /// @param erc1155TokenId The ID of the ERC1155 asset being
          ///        sold. If the given order specifies properties,
          ///        the asset must satisfy those properties. Otherwise,
          ///        it must equal the tokenId in the order.
          /// @param erc1155SellAmount The amount of the ERC1155 asset
          ///        to sell.
          /// @param unwrapNativeToken If this parameter is true and the
          ///        ERC20 token of the order is e.g. WETH, unwraps the
          ///        token before transferring it to the taker.
          /// @param callbackData If this parameter is non-zero, invokes
          ///        `zeroExERC1155OrderCallback` on `msg.sender` after
          ///        the ERC20 tokens have been transferred to `msg.sender`
          ///        but before transferring the ERC1155 asset to the buyer.
          function sellERC1155(
              LibNFTOrder.ERC1155Order calldata buyOrder,
              LibSignature.Signature calldata signature,
              uint256 erc1155TokenId,
              uint128 erc1155SellAmount,
              bool unwrapNativeToken,
              bytes calldata callbackData
          )
              external;
          /// @dev Buys an ERC1155 asset by filling the given order.
          /// @param sellOrder The ERC1155 sell order.
          /// @param signature The order signature.
          /// @param erc1155BuyAmount The amount of the ERC1155 asset
          ///        to buy.
          /// @param callbackData If this parameter is non-zero, invokes
          ///        `zeroExERC1155OrderCallback` on `msg.sender` after
          ///        the ERC1155 asset has been transferred to `msg.sender`
          ///        but before transferring the ERC20 tokens to the seller.
          ///        Native tokens acquired during the callback can be used
          ///        to fill the order.
          function buyERC1155(
              LibNFTOrder.ERC1155Order calldata sellOrder,
              LibSignature.Signature calldata signature,
              uint128 erc1155BuyAmount,
              bytes calldata callbackData
          )
              external
              payable;
          /// @dev Cancel a single ERC1155 order by its nonce. The caller
          ///      should be the maker of the order. Silently succeeds if
          ///      an order with the same nonce has already been filled or
          ///      cancelled.
          /// @param orderNonce The order nonce.
          function cancelERC1155Order(uint256 orderNonce)
              external;
          /// @dev Cancel multiple ERC1155 orders by their nonces. The caller
          ///      should be the maker of the orders. Silently succeeds if
          ///      an order with the same nonce has already been filled or
          ///      cancelled.
          /// @param orderNonces The order nonces.
          function batchCancelERC1155Orders(uint256[] calldata orderNonces)
              external;
          /// @dev Buys multiple ERC1155 assets by filling the
          ///      given orders.
          /// @param sellOrders The ERC1155 sell orders.
          /// @param signatures The order signatures.
          /// @param erc1155TokenAmounts The amounts of the ERC1155 assets
          ///        to buy for each order.
          /// @param callbackData The data (if any) to pass to the taker
          ///        callback for each order. Refer to the `callbackData`
          ///        parameter to for `buyERC1155`.
          /// @param revertIfIncomplete If true, reverts if this
          ///        function fails to fill any individual order.
          /// @return successes An array of booleans corresponding to whether
          ///         each order in `orders` was successfully filled.
          function batchBuyERC1155s(
              LibNFTOrder.ERC1155Order[] calldata sellOrders,
              LibSignature.Signature[] calldata signatures,
              uint128[] calldata erc1155TokenAmounts,
              bytes[] calldata callbackData,
              bool revertIfIncomplete
          )
              external
              payable
              returns (bool[] memory successes);
          /// @dev Callback for the ERC1155 `safeTransferFrom` function.
          ///      This callback can be used to sell an ERC1155 asset if
          ///      a valid ERC1155 order, signature and `unwrapNativeToken`
          ///      are encoded in `data`. This allows takers to sell their
          ///      ERC1155 asset without first calling `setApprovalForAll`.
          /// @param operator The address which called `safeTransferFrom`.
          /// @param from The address which previously owned the token.
          /// @param tokenId The ID of the asset being transferred.
          /// @param value The amount being transferred.
          /// @param data Additional data with no specified format. If a
          ///        valid ERC1155 order, signature and `unwrapNativeToken`
          ///        are encoded in `data`, this function will try to fill
          ///        the order using the received asset.
          /// @return success The selector of this function (0xf23a6e61),
          ///         indicating that the callback succeeded.
          function onERC1155Received(
              address operator,
              address from,
              uint256 tokenId,
              uint256 value,
              bytes calldata data
          )
              external
              returns (bytes4 success);
          /// @dev Approves an ERC1155 order on-chain. After pre-signing
          ///      the order, the `PRESIGNED` signature type will become
          ///      valid for that order and signer.
          /// @param order An ERC1155 order.
          function preSignERC1155Order(LibNFTOrder.ERC1155Order calldata order)
              external;
          /// @dev Checks whether the given signature is valid for the
          ///      the given ERC1155 order. Reverts if not.
          /// @param order The ERC1155 order.
          /// @param signature The signature to validate.
          function validateERC1155OrderSignature(
              LibNFTOrder.ERC1155Order calldata order,
              LibSignature.Signature calldata signature
          )
              external
              view;
          /// @dev If the given order is buying an ERC1155 asset, checks
          ///      whether or not the given token ID satisfies the required
          ///      properties specified in the order. If the order does not
          ///      specify any properties, this function instead checks
          ///      whether the given token ID matches the ID in the order.
          ///      Reverts if any checks fail, or if the order is selling
          ///      an ERC1155 asset.
          /// @param order The ERC1155 order.
          /// @param erc1155TokenId The ID of the ERC1155 asset.
          function validateERC1155OrderProperties(
              LibNFTOrder.ERC1155Order calldata order,
              uint256 erc1155TokenId
          )
              external
              view;
          /// @dev Get the order info for an ERC1155 order.
          /// @param order The ERC1155 order.
          /// @return orderInfo Infor about the order.
          function getERC1155OrderInfo(LibNFTOrder.ERC1155Order calldata order)
              external
              view
              returns (LibNFTOrder.OrderInfo memory orderInfo);
          /// @dev Get the EIP-712 hash of an ERC1155 order.
          /// @param order The ERC1155 order.
          /// @return orderHash The order hash.
          function getERC1155OrderHash(LibNFTOrder.ERC1155Order calldata order)
              external
              view
              returns (bytes32 orderHash);
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2021 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "../../vendor/IERC1155Token.sol";
      import "../../vendor/IERC721Token.sol";
      import "../../vendor/IPropertyValidator.sol";
      /// @dev A library for common NFT order operations.
      library LibNFTOrder {
          enum OrderStatus {
              INVALID,
              FILLABLE,
              UNFILLABLE,
              EXPIRED
          }
          enum TradeDirection {
              SELL_NFT,
              BUY_NFT
          }
          struct Property {
              IPropertyValidator propertyValidator;
              bytes propertyData;
          }
          struct Fee {
              address recipient;
              uint256 amount;
              bytes feeData;
          }
          // "Base struct" for ERC721Order and ERC1155, used
          // by the abstract contract `NFTOrders`.
          struct NFTOrder {
              TradeDirection direction;
              address maker;
              address taker;
              uint256 expiry;
              uint256 nonce;
              IERC20TokenV06 erc20Token;
              uint256 erc20TokenAmount;
              Fee[] fees;
              address nft;
              uint256 nftId;
              Property[] nftProperties;
          }
          // All fields align with those of NFTOrder
          struct ERC721Order {
              TradeDirection direction;
              address maker;
              address taker;
              uint256 expiry;
              uint256 nonce;
              IERC20TokenV06 erc20Token;
              uint256 erc20TokenAmount;
              Fee[] fees;
              IERC721Token erc721Token;
              uint256 erc721TokenId;
              Property[] erc721TokenProperties;
          }
          // All fields except `erc1155TokenAmount` align
          // with those of NFTOrder
          struct ERC1155Order {
              TradeDirection direction;
              address maker;
              address taker;
              uint256 expiry;
              uint256 nonce;
              IERC20TokenV06 erc20Token;
              uint256 erc20TokenAmount;
              Fee[] fees;
              IERC1155Token erc1155Token;
              uint256 erc1155TokenId;
              Property[] erc1155TokenProperties;
              // End of fields shared with NFTOrder
              uint128 erc1155TokenAmount;
          }
          struct OrderInfo {
              bytes32 orderHash;
              OrderStatus status;
              // `orderAmount` is 1 for all ERC721Orders, and
              // `erc1155TokenAmount` for ERC1155Orders.
              uint128 orderAmount;
              // The remaining amount of the ERC721/ERC1155 asset
              // that can be filled for the order.
              uint128 remainingAmount;
          }
          // The type hash for ERC721 orders, which is:
          // keccak256(abi.encodePacked(
          //     "ERC721Order(",
          //       "uint8 direction,",
          //       "address maker,",
          //       "address taker,",
          //       "uint256 expiry,",
          //       "uint256 nonce,",
          //       "address erc20Token,",
          //       "uint256 erc20TokenAmount,",
          //       "Fee[] fees,",
          //       "address erc721Token,",
          //       "uint256 erc721TokenId,",
          //       "Property[] erc721TokenProperties",
          //     ")",
          //     "Fee(",
          //       "address recipient,",
          //       "uint256 amount,",
          //       "bytes feeData",
          //     ")",
          //     "Property(",
          //       "address propertyValidator,",
          //       "bytes propertyData",
          //     ")"
          // ))
          uint256 private constant _ERC_721_ORDER_TYPEHASH =
              0x2de32b2b090da7d8ab83ca4c85ba2eb6957bc7f6c50cb4ae1995e87560d808ed;
          // The type hash for ERC1155 orders, which is:
          // keccak256(abi.encodePacked(
          //     "ERC1155Order(",
          //       "uint8 direction,",
          //       "address maker,",
          //       "address taker,",
          //       "uint256 expiry,",
          //       "uint256 nonce,",
          //       "address erc20Token,",
          //       "uint256 erc20TokenAmount,",
          //       "Fee[] fees,",
          //       "address erc1155Token,",
          //       "uint256 erc1155TokenId,",
          //       "Property[] erc1155TokenProperties,",
          //       "uint128 erc1155TokenAmount",
          //     ")",
          //     "Fee(",
          //       "address recipient,",
          //       "uint256 amount,",
          //       "bytes feeData",
          //     ")",
          //     "Property(",
          //       "address propertyValidator,",
          //       "bytes propertyData",
          //     ")"
          // ))
          uint256 private constant _ERC_1155_ORDER_TYPEHASH =
              0x930490b1bcedd2e5139e22c761fafd52e533960197c2283f3922c7fd8c880be9;
          // keccak256(abi.encodePacked(
          //     "Fee(",
          //       "address recipient,",
          //       "uint256 amount,",
          //       "bytes feeData",
          //     ")"
          // ))
          uint256 private constant _FEE_TYPEHASH =
              0xe68c29f1b4e8cce0bbcac76eb1334bdc1dc1f293a517c90e9e532340e1e94115;
          // keccak256(abi.encodePacked(
          //     "Property(",
          //       "address propertyValidator,",
          //       "bytes propertyData",
          //     ")"
          // ))
          uint256 private constant _PROPERTY_TYPEHASH =
              0x6292cf854241cb36887e639065eca63b3af9f7f70270cebeda4c29b6d3bc65e8;
          // keccak256("");
          bytes32 private constant _EMPTY_ARRAY_KECCAK256 =
              0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
          // keccak256(abi.encodePacked(keccak256(abi.encode(
          //     _PROPERTY_TYPEHASH,
          //     address(0),
          //     keccak256("")
          // ))));
          bytes32 private constant _NULL_PROPERTY_STRUCT_HASH =
              0x720ee400a9024f6a49768142c339bf09d2dd9056ab52d20fbe7165faba6e142d;
          uint256 private constant ADDRESS_MASK = (1 << 160) - 1;
          // ERC721Order and NFTOrder fields are aligned, so
          // we can safely cast an ERC721Order to an NFTOrder.
          function asNFTOrder(ERC721Order memory erc721Order)
              internal
              pure
              returns (NFTOrder memory nftOrder)
          {
              assembly {
                  nftOrder := erc721Order
              }
          }
          // ERC1155Order and NFTOrder fields are aligned with
          // the exception of the last field `erc1155TokenAmount`
          // in ERC1155Order, so we can safely cast an ERC1155Order
          // to an NFTOrder.
          function asNFTOrder(ERC1155Order memory erc1155Order)
              internal
              pure
              returns (NFTOrder memory nftOrder)
          {
              assembly {
                  nftOrder := erc1155Order
              }
          }
          // ERC721Order and NFTOrder fields are aligned, so
          // we can safely cast an MFTOrder to an ERC721Order.
          function asERC721Order(NFTOrder memory nftOrder)
              internal
              pure
              returns (ERC721Order memory erc721Order)
          {
              assembly {
                  erc721Order := nftOrder
              }
          }
          // NOTE: This is only safe if `nftOrder` was previously
          // cast from an `ERC1155Order` and the original
          // `erc1155TokenAmount` memory word has not been corrupted!
          function asERC1155Order(
              NFTOrder memory nftOrder
          )
              internal
              pure
              returns (ERC1155Order memory erc1155Order)
          {
              assembly {
                  erc1155Order := nftOrder
              }
          }
          /// @dev Get the struct hash of an ERC721 order.
          /// @param order The ERC721 order.
          /// @return structHash The struct hash of the order.
          function getERC721OrderStructHash(ERC721Order memory order)
              internal
              pure
              returns (bytes32 structHash)
          {
              bytes32 propertiesHash = _propertiesHash(order.erc721TokenProperties);
              bytes32 feesHash = _feesHash(order.fees);
              // Hash in place, equivalent to:
              // return keccak256(abi.encode(
              //     _ERC_721_ORDER_TYPEHASH,
              //     order.direction,
              //     order.maker,
              //     order.taker,
              //     order.expiry,
              //     order.nonce,
              //     order.erc20Token,
              //     order.erc20TokenAmount,
              //     feesHash,
              //     order.erc721Token,
              //     order.erc721TokenId,
              //     propertiesHash
              // ));
              assembly {
                  if lt(order, 32) { invalid() } // Don't underflow memory.
                  let typeHashPos := sub(order, 32) // order - 32
                  let feesHashPos := add(order, 224) // order + (32 * 7)
                  let propertiesHashPos := add(order, 320) // order + (32 * 10)
                  let typeHashMemBefore := mload(typeHashPos)
                  let feeHashMemBefore := mload(feesHashPos)
                  let propertiesHashMemBefore := mload(propertiesHashPos)
                  mstore(typeHashPos, _ERC_721_ORDER_TYPEHASH)
                  mstore(feesHashPos, feesHash)
                  mstore(propertiesHashPos, propertiesHash)
                  structHash := keccak256(typeHashPos, 384 /* 32 * 12 */ )
                  mstore(typeHashPos, typeHashMemBefore)
                  mstore(feesHashPos, feeHashMemBefore)
                  mstore(propertiesHashPos, propertiesHashMemBefore)
              }
              return structHash;
          }
          /// @dev Get the struct hash of an ERC1155 order.
          /// @param order The ERC1155 order.
          /// @return structHash The struct hash of the order.
          function getERC1155OrderStructHash(ERC1155Order memory order)
              internal
              pure
              returns (bytes32 structHash)
          {
              bytes32 propertiesHash = _propertiesHash(order.erc1155TokenProperties);
              bytes32 feesHash = _feesHash(order.fees);
              // Hash in place, equivalent to:
              // return keccak256(abi.encode(
              //     _ERC_1155_ORDER_TYPEHASH,
              //     order.direction,
              //     order.maker,
              //     order.taker,
              //     order.expiry,
              //     order.nonce,
              //     order.erc20Token,
              //     order.erc20TokenAmount,
              //     feesHash,
              //     order.erc1155Token,
              //     order.erc1155TokenId,
              //     propertiesHash,
              //     order.erc1155TokenAmount
              // ));
              assembly {
                  if lt(order, 32) { invalid() } // Don't underflow memory.
                  let typeHashPos := sub(order, 32) // order - 32
                  let feesHashPos := add(order, 224) // order + (32 * 7)
                  let propertiesHashPos := add(order, 320) // order + (32 * 10)
                  let typeHashMemBefore := mload(typeHashPos)
                  let feesHashMemBefore := mload(feesHashPos)
                  let propertiesHashMemBefore := mload(propertiesHashPos)
                  mstore(typeHashPos, _ERC_1155_ORDER_TYPEHASH)
                  mstore(feesHashPos, feesHash)
                  mstore(propertiesHashPos, propertiesHash)
                  structHash := keccak256(typeHashPos, 416 /* 32 * 12 */ )
                  mstore(typeHashPos, typeHashMemBefore)
                  mstore(feesHashPos, feesHashMemBefore)
                  mstore(propertiesHashPos, propertiesHashMemBefore)
              }
              return structHash;
          }
          // Hashes the `properties` arrayB as part of computing the
          // EIP-712 hash of an `ERC721Order` or `ERC1155Order`.
          function _propertiesHash(Property[] memory properties)
              private
              pure
              returns (bytes32 propertiesHash)
          {
              uint256 numProperties = properties.length;
              // We give `properties.length == 0` and `properties.length == 1`
              // special treatment because we expect these to be the most common.
              if (numProperties == 0) {
                  propertiesHash = _EMPTY_ARRAY_KECCAK256;
              } else if (numProperties == 1) {
                  Property memory property = properties[0];
                  if (
                      address(property.propertyValidator) == address(0) &&
                      property.propertyData.length == 0
                  ) {
                      propertiesHash = _NULL_PROPERTY_STRUCT_HASH;
                  } else {
                      // propertiesHash = keccak256(abi.encodePacked(keccak256(abi.encode(
                      //     _PROPERTY_TYPEHASH,
                      //     properties[0].propertyValidator,
                      //     keccak256(properties[0].propertyData)
                      // ))));
                      bytes32 dataHash = keccak256(property.propertyData);
                      assembly {
                          // Load free memory pointer
                          let mem := mload(64)
                          mstore(mem, _PROPERTY_TYPEHASH)
                          // property.propertyValidator
                          mstore(add(mem, 32), and(ADDRESS_MASK, mload(property)))
                          // keccak256(property.propertyData)
                          mstore(add(mem, 64), dataHash)
                          mstore(mem, keccak256(mem, 96))
                          propertiesHash := keccak256(mem, 32)
                      }
                  }
              } else {
                  bytes32[] memory propertyStructHashArray = new bytes32[](numProperties);
                  for (uint256 i = 0; i < numProperties; i++) {
                      propertyStructHashArray[i] = keccak256(abi.encode(
                          _PROPERTY_TYPEHASH,
                          properties[i].propertyValidator,
                          keccak256(properties[i].propertyData)
                      ));
                  }
                  assembly {
                      propertiesHash := keccak256(add(propertyStructHashArray, 32), mul(numProperties, 32))
                  }
              }
          }
          // Hashes the `fees` arrayB as part of computing the
          // EIP-712 hash of an `ERC721Order` or `ERC1155Order`.
          function _feesHash(Fee[] memory fees)
              private
              pure
              returns (bytes32 feesHash)
          {
              uint256 numFees = fees.length;
              // We give `fees.length == 0` and `fees.length == 1`
              // special treatment because we expect these to be the most common.
              if (numFees == 0) {
                  feesHash = _EMPTY_ARRAY_KECCAK256;
              } else if (numFees == 1) {
                  // feesHash = keccak256(abi.encodePacked(keccak256(abi.encode(
                  //     _FEE_TYPEHASH,
                  //     fees[0].recipient,
                  //     fees[0].amount,
                  //     keccak256(fees[0].feeData)
                  // ))));
                  Fee memory fee = fees[0];
                  bytes32 dataHash = keccak256(fee.feeData);
                  assembly {
                      // Load free memory pointer
                      let mem := mload(64)
                      mstore(mem, _FEE_TYPEHASH)
                      // fee.recipient
                      mstore(add(mem, 32), and(ADDRESS_MASK, mload(fee)))
                      // fee.amount
                      mstore(add(mem, 64), mload(add(fee, 32)))
                      // keccak256(fee.feeData)
                      mstore(add(mem, 96), dataHash)
                      mstore(mem, keccak256(mem, 128))
                      feesHash := keccak256(mem, 32)
                  }
              } else {
                  bytes32[] memory feeStructHashArray = new bytes32[](numFees);
                  for (uint256 i = 0; i < numFees; i++) {
                      feeStructHashArray[i] = keccak256(abi.encode(
                          _FEE_TYPEHASH,
                          fees[i].recipient,
                          fees[i].amount,
                          keccak256(fees[i].feeData)
                      ));
                  }
                  assembly {
                      feesHash := keccak256(add(feeStructHashArray, 32), mul(numFees, 32))
                  }
              }
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2021 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      interface IERC721Token {
          /// @dev This emits when ownership of any NFT changes by any mechanism.
          ///      This event emits when NFTs are created (`from` == 0) and destroyed
          ///      (`to` == 0). Exception: during contract creation, any number of NFTs
          ///      may be created and assigned without emitting Transfer. At the time of
          ///      any transfer, the approved address for that NFT (if any) is reset to none.
          event Transfer(
              address indexed _from,
              address indexed _to,
              uint256 indexed _tokenId
          );
          /// @dev This emits when the approved address for an NFT is changed or
          ///      reaffirmed. The zero address indicates there is no approved address.
          ///      When a Transfer event emits, this also indicates that the approved
          ///      address for that NFT (if any) is reset to none.
          event Approval(
              address indexed _owner,
              address indexed _approved,
              uint256 indexed _tokenId
          );
          /// @dev This emits when an operator is enabled or disabled for an owner.
          ///      The operator can manage all NFTs of the owner.
          event ApprovalForAll(
              address indexed _owner,
              address indexed _operator,
              bool _approved
          );
          /// @notice Transfers the ownership of an NFT from one address to another address
          /// @dev Throws unless `msg.sender` is the current owner, an authorized
          ///      perator, or the approved address for this NFT. Throws if `_from` is
          ///      not the current owner. Throws if `_to` is the zero address. Throws if
          ///      `_tokenId` is not a valid NFT. When transfer is complete, this function
          ///      checks if `_to` is a smart contract (code size > 0). If so, it calls
          ///      `onERC721Received` on `_to` and throws if the return value is not
          ///      `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`.
          /// @param _from The current owner of the NFT
          /// @param _to The new owner
          /// @param _tokenId The NFT to transfer
          /// @param _data Additional data with no specified format, sent in call to `_to`
          function safeTransferFrom(
              address _from,
              address _to,
              uint256 _tokenId,
              bytes calldata _data
          )
              external;
          /// @notice Transfers the ownership of an NFT from one address to another address
          /// @dev This works identically to the other function with an extra data parameter,
          ///      except this function just sets data to "".
          /// @param _from The current owner of the NFT
          /// @param _to The new owner
          /// @param _tokenId The NFT to transfer
          function safeTransferFrom(
              address _from,
              address _to,
              uint256 _tokenId
          )
              external;
          /// @notice Change or reaffirm the approved address for an NFT
          /// @dev The zero address indicates there is no approved address.
          ///      Throws unless `msg.sender` is the current NFT owner, or an authorized
          ///      operator of the current owner.
          /// @param _approved The new approved NFT controller
          /// @param _tokenId The NFT to approve
          function approve(address _approved, uint256 _tokenId)
              external;
          /// @notice Enable or disable approval for a third party ("operator") to manage
          ///         all of `msg.sender`'s assets
          /// @dev Emits the ApprovalForAll event. The contract MUST allow
          ///      multiple operators per owner.
          /// @param _operator Address to add to the set of authorized operators
          /// @param _approved True if the operator is approved, false to revoke approval
          function setApprovalForAll(address _operator, bool _approved)
              external;
          /// @notice Count all NFTs assigned to an owner
          /// @dev NFTs assigned to the zero address are considered invalid, and this
          ///      function throws for queries about the zero address.
          /// @param _owner An address for whom to query the balance
          /// @return The number of NFTs owned by `_owner`, possibly zero
          function balanceOf(address _owner)
              external
              view
              returns (uint256);
          /// @notice Transfer ownership of an NFT -- THE CALLER IS RESPONSIBLE
          ///         TO CONFIRM THAT `_to` IS CAPABLE OF RECEIVING NFTS OR ELSE
          ///         THEY MAY BE PERMANENTLY LOST
          /// @dev Throws unless `msg.sender` is the current owner, an authorized
          ///      operator, or the approved address for this NFT. Throws if `_from` is
          ///      not the current owner. Throws if `_to` is the zero address. Throws if
          ///      `_tokenId` is not a valid NFT.
          /// @param _from The current owner of the NFT
          /// @param _to The new owner
          /// @param _tokenId The NFT to transfer
          function transferFrom(
              address _from,
              address _to,
              uint256 _tokenId
          )
              external;
          /// @notice Find the owner of an NFT
          /// @dev NFTs assigned to zero address are considered invalid, and queries
          ///      about them do throw.
          /// @param _tokenId The identifier for an NFT
          /// @return The address of the owner of the NFT
          function ownerOf(uint256 _tokenId)
              external
              view
              returns (address);
          /// @notice Get the approved address for a single NFT
          /// @dev Throws if `_tokenId` is not a valid NFT.
          /// @param _tokenId The NFT to find the approved address for
          /// @return The approved address for this NFT, or the zero address if there is none
          function getApproved(uint256 _tokenId)
              external
              view
              returns (address);
          /// @notice Query if an address is an authorized operator for another address
          /// @param _owner The address that owns the NFTs
          /// @param _operator The address that acts on behalf of the owner
          /// @return True if `_operator` is an approved operator for `_owner`, false otherwise
          function isApprovedForAll(address _owner, address _operator)
              external
              view
              returns (bool);
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2021 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      pragma experimental ABIEncoderV2;
      interface IPropertyValidator {
          /// @dev Checks that the given ERC721/ERC1155 asset satisfies the properties encoded in `propertyData`.
          ///      Should revert if the asset does not satisfy the specified properties.
          /// @param tokenAddress The ERC721/ERC1155 token contract address.
          /// @param tokenId The ERC721/ERC1155 tokenId of the asset to check.
          /// @param propertyData Encoded properties or auxiliary data needed to perform the check.
          function validateProperty(
              address tokenAddress,
              uint256 tokenId,
              bytes calldata propertyData
          )
              external
              view;
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "../../errors/LibSignatureRichErrors.sol";
      /// @dev A library for validating signatures.
      library LibSignature {
          using LibRichErrorsV06 for bytes;
          // '\\x19Ethereum Signed Message:\
      32\\x00\\x00\\x00\\x00' in a word.
          uint256 private constant ETH_SIGN_HASH_PREFIX =
              0x19457468657265756d205369676e6564204d6573736167653a0a333200000000;
          /// @dev Exclusive upper limit on ECDSA signatures 'R' values.
          ///      The valid range is given by fig (282) of the yellow paper.
          uint256 private constant ECDSA_SIGNATURE_R_LIMIT =
              uint256(0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141);
          /// @dev Exclusive upper limit on ECDSA signatures 'S' values.
          ///      The valid range is given by fig (283) of the yellow paper.
          uint256 private constant ECDSA_SIGNATURE_S_LIMIT = ECDSA_SIGNATURE_R_LIMIT / 2 + 1;
          /// @dev Allowed signature types.
          enum SignatureType {
              ILLEGAL,
              INVALID,
              EIP712,
              ETHSIGN,
              PRESIGNED
          }
          /// @dev Encoded EC signature.
          struct Signature {
              // How to validate the signature.
              SignatureType signatureType;
              // EC Signature data.
              uint8 v;
              // EC Signature data.
              bytes32 r;
              // EC Signature data.
              bytes32 s;
          }
          /// @dev Retrieve the signer of a signature.
          ///      Throws if the signature can't be validated.
          /// @param hash The hash that was signed.
          /// @param signature The signature.
          /// @return recovered The recovered signer address.
          function getSignerOfHash(
              bytes32 hash,
              Signature memory signature
          )
              internal
              pure
              returns (address recovered)
          {
              // Ensure this is a signature type that can be validated against a hash.
              _validateHashCompatibleSignature(hash, signature);
              if (signature.signatureType == SignatureType.EIP712) {
                  // Signed using EIP712
                  recovered = ecrecover(
                      hash,
                      signature.v,
                      signature.r,
                      signature.s
                  );
              } else if (signature.signatureType == SignatureType.ETHSIGN) {
                  // Signed using `eth_sign`
                  // Need to hash `hash` with "\\x19Ethereum Signed Message:\
      32" prefix
                  // in packed encoding.
                  bytes32 ethSignHash;
                  assembly {
                      // Use scratch space
                      mstore(0, ETH_SIGN_HASH_PREFIX) // length of 28 bytes
                      mstore(28, hash) // length of 32 bytes
                      ethSignHash := keccak256(0, 60)
                  }
                  recovered = ecrecover(
                      ethSignHash,
                      signature.v,
                      signature.r,
                      signature.s
                  );
              }
              // `recovered` can be null if the signature values are out of range.
              if (recovered == address(0)) {
                  LibSignatureRichErrors.SignatureValidationError(
                      LibSignatureRichErrors.SignatureValidationErrorCodes.BAD_SIGNATURE_DATA,
                      hash
                  ).rrevert();
              }
          }
          /// @dev Validates that a signature is compatible with a hash signee.
          /// @param hash The hash that was signed.
          /// @param signature The signature.
          function _validateHashCompatibleSignature(
              bytes32 hash,
              Signature memory signature
          )
              private
              pure
          {
              // Ensure the r and s are within malleability limits.
              if (uint256(signature.r) >= ECDSA_SIGNATURE_R_LIMIT ||
                  uint256(signature.s) >= ECDSA_SIGNATURE_S_LIMIT)
              {
                  LibSignatureRichErrors.SignatureValidationError(
                      LibSignatureRichErrors.SignatureValidationErrorCodes.BAD_SIGNATURE_DATA,
                      hash
                  ).rrevert();
              }
              // Always illegal signature.
              if (signature.signatureType == SignatureType.ILLEGAL) {
                  LibSignatureRichErrors.SignatureValidationError(
                      LibSignatureRichErrors.SignatureValidationErrorCodes.ILLEGAL,
                      hash
                  ).rrevert();
              }
              // Always invalid.
              if (signature.signatureType == SignatureType.INVALID) {
                  LibSignatureRichErrors.SignatureValidationError(
                      LibSignatureRichErrors.SignatureValidationErrorCodes.ALWAYS_INVALID,
                      hash
                  ).rrevert();
              }
              // If a feature supports pre-signing, it wouldn't use 
              // `getSignerOfHash` on a pre-signed order.
              if (signature.signatureType == SignatureType.PRESIGNED) {
                  LibSignatureRichErrors.SignatureValidationError(
                      LibSignatureRichErrors.SignatureValidationErrorCodes.UNSUPPORTED,
                      hash
                  ).rrevert();
              }
              // Solidity should check that the signature type is within enum range for us
              // when abi-decoding.
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibSignatureRichErrors {
          enum SignatureValidationErrorCodes {
              ALWAYS_INVALID,
              INVALID_LENGTH,
              UNSUPPORTED,
              ILLEGAL,
              WRONG_SIGNER,
              BAD_SIGNATURE_DATA
          }
          // solhint-disable func-name-mixedcase
          function SignatureValidationError(
              SignatureValidationErrorCodes code,
              bytes32 hash,
              address signerAddress,
              bytes memory signature
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("SignatureValidationError(uint8,bytes32,address,bytes)")),
                  code,
                  hash,
                  signerAddress,
                  signature
              );
          }
          function SignatureValidationError(
              SignatureValidationErrorCodes code,
              bytes32 hash
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("SignatureValidationError(uint8,bytes32)")),
                  code,
                  hash
              );
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2021 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "@0x/contracts-erc20/contracts/src/v06/IEtherTokenV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibMathV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
      import "../../errors/LibNFTOrdersRichErrors.sol";
      import "../../fixins/FixinCommon.sol";
      import "../../fixins/FixinEIP712.sol";
      import "../../fixins/FixinTokenSpender.sol";
      import "../../migrations/LibMigrate.sol";
      import "../../vendor/IFeeRecipient.sol";
      import "../../vendor/ITakerCallback.sol";
      import "../libs/LibSignature.sol";
      import "../libs/LibNFTOrder.sol";
      /// @dev Abstract base contract inherited by ERC721OrdersFeature and NFTOrders
      abstract contract NFTOrders is
          FixinCommon,
          FixinEIP712,
          FixinTokenSpender
      {
          using LibSafeMathV06 for uint256;
          /// @dev Native token pseudo-address.
          address constant internal NATIVE_TOKEN_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
          /// @dev The WETH token contract.
          IEtherTokenV06 internal immutable WETH;
          /// @dev The magic return value indicating the success of a `receiveZeroExFeeCallback`.
          bytes4 private constant FEE_CALLBACK_MAGIC_BYTES = IFeeRecipient.receiveZeroExFeeCallback.selector;
          /// @dev The magic return value indicating the success of a `zeroExTakerCallback`.
          bytes4 private constant TAKER_CALLBACK_MAGIC_BYTES = ITakerCallback.zeroExTakerCallback.selector;
          constructor(address zeroExAddress, IEtherTokenV06 weth)
              public
              FixinEIP712(zeroExAddress)
          {
              WETH = weth;
          }
          struct SellParams {
              uint128 sellAmount;
              uint256 tokenId;
              bool unwrapNativeToken;
              address taker;
              address currentNftOwner;
              bytes takerCallbackData;
          }
          struct BuyParams {
              uint128 buyAmount;
              uint256 ethAvailable;
              bytes takerCallbackData;
          }
          // Core settlement logic for selling an NFT asset.
          function _sellNFT(
              LibNFTOrder.NFTOrder memory buyOrder,
              LibSignature.Signature memory signature,
              SellParams memory params
          )
              internal
              returns (uint256 erc20FillAmount)
          {
              LibNFTOrder.OrderInfo memory orderInfo = _getOrderInfo(buyOrder);
              // Check that the order can be filled.
              _validateBuyOrder(
                  buyOrder,
                  signature,
                  orderInfo,
                  params.taker,
                  params.tokenId
              );
              if (params.sellAmount > orderInfo.remainingAmount) {
                  LibNFTOrdersRichErrors.ExceedsRemainingOrderAmount(
                      orderInfo.remainingAmount,
                      params.sellAmount
                  ).rrevert();
              }
              _updateOrderState(buyOrder, orderInfo.orderHash, params.sellAmount);
              if (params.sellAmount == orderInfo.orderAmount) {
                  erc20FillAmount = buyOrder.erc20TokenAmount;
              } else {
                  // Rounding favors the order maker.
                  erc20FillAmount = LibMathV06.getPartialAmountFloor(
                      params.sellAmount,
                      orderInfo.orderAmount,
                      buyOrder.erc20TokenAmount
                  );
              }
              if (params.unwrapNativeToken) {
                  // The ERC20 token must be WETH for it to be unwrapped.
                  if (buyOrder.erc20Token != WETH) {
                      LibNFTOrdersRichErrors.ERC20TokenMismatchError(
                          address(buyOrder.erc20Token),
                          address(WETH)
                      ).rrevert();
                  }
                  // Transfer the WETH from the maker to the Exchange Proxy
                  // so we can unwrap it before sending it to the seller.
                  // TODO: Probably safe to just use WETH.transferFrom for some
                  //       small gas savings
                  _transferERC20TokensFrom(
                      WETH,
                      buyOrder.maker,
                      address(this),
                      erc20FillAmount
                  );
                  // Unwrap WETH into ETH.
                  WETH.withdraw(erc20FillAmount);
                  // Send ETH to the seller.
                  _transferEth(payable(params.taker), erc20FillAmount);
              } else {
                  // Transfer the ERC20 token from the buyer to the seller.
                  _transferERC20TokensFrom(
                      buyOrder.erc20Token,
                      buyOrder.maker,
                      params.taker,
                      erc20FillAmount
                  );
              }
              if (params.takerCallbackData.length > 0) {
                  require(
                      params.taker != address(this),
                      "NFTOrders::_sellNFT/CANNOT_CALLBACK_SELF"
                  );
                  // Invoke the callback
                  bytes4 callbackResult = ITakerCallback(params.taker)
                      .zeroExTakerCallback(orderInfo.orderHash, params.takerCallbackData);
                  // Check for the magic success bytes
                  require(
                      callbackResult == TAKER_CALLBACK_MAGIC_BYTES,
                      "NFTOrders::_sellNFT/CALLBACK_FAILED"
                  );
              }
              // Transfer the NFT asset to the buyer.
              // If this function is called from the
              // `onNFTReceived` callback the Exchange Proxy
              // holds the asset. Otherwise, transfer it from
              // the seller.
              _transferNFTAssetFrom(
                  buyOrder.nft,
                  params.currentNftOwner,
                  buyOrder.maker,
                  params.tokenId,
                  params.sellAmount
              );
              // The buyer pays the order fees.
              _payFees(
                  buyOrder,
                  buyOrder.maker,
                  params.sellAmount,
                  orderInfo.orderAmount,
                  false
              );
          }
          // Core settlement logic for buying an NFT asset.
          function _buyNFT(
              LibNFTOrder.NFTOrder memory sellOrder,
              LibSignature.Signature memory signature,
              BuyParams memory params
          )
              internal
              returns (uint256 erc20FillAmount)
          {
              LibNFTOrder.OrderInfo memory orderInfo = _getOrderInfo(sellOrder);
              // Check that the order can be filled.
              _validateSellOrder(
                  sellOrder,
                  signature,
                  orderInfo,
                  msg.sender
              );
              if (params.buyAmount > orderInfo.remainingAmount) {
                  LibNFTOrdersRichErrors.ExceedsRemainingOrderAmount(
                      orderInfo.remainingAmount,
                      params.buyAmount
                  ).rrevert();
              }
              _updateOrderState(sellOrder, orderInfo.orderHash, params.buyAmount);
              if (params.buyAmount == orderInfo.orderAmount) {
                  erc20FillAmount = sellOrder.erc20TokenAmount;
              } else {
                  // Rounding favors the order maker.
                  erc20FillAmount = LibMathV06.getPartialAmountCeil(
                      params.buyAmount,
                      orderInfo.orderAmount,
                      sellOrder.erc20TokenAmount
                  );
              }
              // Transfer the NFT asset to the buyer (`msg.sender`).
              _transferNFTAssetFrom(
                  sellOrder.nft,
                  sellOrder.maker,
                  msg.sender,
                  sellOrder.nftId,
                  params.buyAmount
              );
              uint256 ethAvailable = params.ethAvailable;
              if (params.takerCallbackData.length > 0) {
                  require(
                      msg.sender != address(this),
                      "NFTOrders::_buyNFT/CANNOT_CALLBACK_SELF"
                  );
                  uint256 ethBalanceBeforeCallback = address(this).balance;
                  // Invoke the callback
                  bytes4 callbackResult = ITakerCallback(msg.sender)
                      .zeroExTakerCallback(orderInfo.orderHash, params.takerCallbackData);
                  // Update `ethAvailable` with amount acquired during
                  // the callback
                  ethAvailable = ethAvailable.safeAdd(
                      address(this).balance.safeSub(ethBalanceBeforeCallback)
                  );
                  // Check for the magic success bytes
                  require(
                      callbackResult == TAKER_CALLBACK_MAGIC_BYTES,
                      "NFTOrders::_buyNFT/CALLBACK_FAILED"
                  );
              }
              if (address(sellOrder.erc20Token) == NATIVE_TOKEN_ADDRESS) {
                  // Transfer ETH to the seller.
                  _transferEth(payable(sellOrder.maker), erc20FillAmount);
                  // Fees are paid from the EP's current balance of ETH.
                  _payEthFees(
                      sellOrder,
                      params.buyAmount,
                      orderInfo.orderAmount,
                      erc20FillAmount,
                      ethAvailable
                  );
              } else if (sellOrder.erc20Token == WETH) {
                  // If there is enough ETH available, fill the WETH order
                  // (including fees) using that ETH.
                  // Otherwise, transfer WETH from the taker.
                  if (ethAvailable >= erc20FillAmount) {
                      // Wrap ETH.
                      WETH.deposit{value: erc20FillAmount}();
                      // TODO: Probably safe to just use WETH.transfer for some
                      //       small gas savings
                      // Transfer WETH to the seller.
                      _transferERC20Tokens(
                          WETH,
                          sellOrder.maker,
                          erc20FillAmount
                      );
                      // Fees are paid from the EP's current balance of ETH.
                      _payEthFees(
                          sellOrder,
                          params.buyAmount,
                          orderInfo.orderAmount,
                          erc20FillAmount,
                          ethAvailable
                      );
                  } else {
                      // Transfer WETH from the buyer to the seller.
                      _transferERC20TokensFrom(
                          sellOrder.erc20Token,
                          msg.sender,
                          sellOrder.maker,
                          erc20FillAmount
                      );
                      // The buyer pays fees using WETH.
                      _payFees(
                          sellOrder,
                          msg.sender,
                          params.buyAmount,
                          orderInfo.orderAmount,
                          false
                      );
                  }
              } else {
                  // Transfer ERC20 token from the buyer to the seller.
                  _transferERC20TokensFrom(
                      sellOrder.erc20Token,
                      msg.sender,
                      sellOrder.maker,
                      erc20FillAmount
                  );
                  // The buyer pays fees.
                  _payFees(
                      sellOrder,
                      msg.sender,
                      params.buyAmount,
                      orderInfo.orderAmount,
                      false
                  );
              }
          }
          function _validateSellOrder(
              LibNFTOrder.NFTOrder memory sellOrder,
              LibSignature.Signature memory signature,
              LibNFTOrder.OrderInfo memory orderInfo,
              address taker
          )
              internal
              view
          {
              // Order must be selling the NFT asset.
              require(
                  sellOrder.direction == LibNFTOrder.TradeDirection.SELL_NFT,
                  "NFTOrders::_validateSellOrder/WRONG_TRADE_DIRECTION"
              );
              // Taker must match the order taker, if one is specified.
              if (sellOrder.taker != address(0) && sellOrder.taker != taker) {
                  LibNFTOrdersRichErrors.OnlyTakerError(taker, sellOrder.taker).rrevert();
              }
              // Check that the order is valid and has not expired, been cancelled,
              // or been filled.
              if (orderInfo.status != LibNFTOrder.OrderStatus.FILLABLE) {
                  LibNFTOrdersRichErrors.OrderNotFillableError(
                      sellOrder.maker,
                      sellOrder.nonce,
                      uint8(orderInfo.status)
                  ).rrevert();
              }
              // Check the signature.
              _validateOrderSignature(orderInfo.orderHash, signature, sellOrder.maker);
          }
          function _validateBuyOrder(
              LibNFTOrder.NFTOrder memory buyOrder,
              LibSignature.Signature memory signature,
              LibNFTOrder.OrderInfo memory orderInfo,
              address taker,
              uint256 tokenId
          )
              internal
              view
          {
              // Order must be buying the NFT asset.
              require(
                  buyOrder.direction == LibNFTOrder.TradeDirection.BUY_NFT,
                  "NFTOrders::_validateBuyOrder/WRONG_TRADE_DIRECTION"
              );
              // The ERC20 token cannot be ETH.
              require(
                  address(buyOrder.erc20Token) != NATIVE_TOKEN_ADDRESS,
                  "NFTOrders::_validateBuyOrder/NATIVE_TOKEN_NOT_ALLOWED"
              );
              // Taker must match the order taker, if one is specified.
              if (buyOrder.taker != address(0) && buyOrder.taker != taker) {
                  LibNFTOrdersRichErrors.OnlyTakerError(taker, buyOrder.taker).rrevert();
              }
              // Check that the order is valid and has not expired, been cancelled,
              // or been filled.
              if (orderInfo.status != LibNFTOrder.OrderStatus.FILLABLE) {
                  LibNFTOrdersRichErrors.OrderNotFillableError(
                      buyOrder.maker,
                      buyOrder.nonce,
                      uint8(orderInfo.status)
                  ).rrevert();
              }
              // Check that the asset with the given token ID satisfies the properties
              // specified by the order.
              _validateOrderProperties(buyOrder, tokenId);
              // Check the signature.
              _validateOrderSignature(orderInfo.orderHash, signature, buyOrder.maker);
          }
          function _payEthFees(
              LibNFTOrder.NFTOrder memory order,
              uint128 fillAmount,
              uint128 orderAmount,
              uint256 ethSpent,
              uint256 ethAvailable
          )
              private
          {
              // Pay fees using ETH.
              uint256 ethFees = _payFees(
                  order,
                  address(this),
                  fillAmount,
                  orderAmount,
                  true
              );
              // Update amount of ETH spent.
              ethSpent = ethSpent.safeAdd(ethFees);
              if (ethSpent > ethAvailable) {
                  LibNFTOrdersRichErrors.OverspentEthError(
                      ethSpent,
                      ethAvailable
                  ).rrevert();
              }
          }
          function _payFees(
              LibNFTOrder.NFTOrder memory order,
              address payer,
              uint128 fillAmount,
              uint128 orderAmount,
              bool useNativeToken
          )
              internal
              returns (uint256 totalFeesPaid)
          {
              // Make assertions about ETH case
              if (useNativeToken) {
                  assert(payer == address(this));
                  assert(
                      order.erc20Token == WETH ||
                      address(order.erc20Token) == NATIVE_TOKEN_ADDRESS
                  );
              }
              for (uint256 i = 0; i < order.fees.length; i++) {
                  LibNFTOrder.Fee memory fee = order.fees[i];
                  require(
                      fee.recipient != address(this),
                      "NFTOrders::_payFees/RECIPIENT_CANNOT_BE_EXCHANGE_PROXY"
                  );
                  uint256 feeFillAmount;
                  if (fillAmount == orderAmount) {
                      feeFillAmount = fee.amount;
                  } else {
                      // Round against the fee recipient
                      feeFillAmount = LibMathV06.getPartialAmountFloor(
                          fillAmount,
                          orderAmount,
                          fee.amount
                      );
                  }
                  if (feeFillAmount == 0) {
                      continue;
                  }
                  if (useNativeToken) {
                      // Transfer ETH to the fee recipient.
                      _transferEth(payable(fee.recipient), feeFillAmount);
                  } else {
                      // Transfer ERC20 token from payer to recipient.
                      _transferERC20TokensFrom(
                          order.erc20Token,
                          payer,
                          fee.recipient,
                          feeFillAmount
                      );
                  }
                  // Note that the fee callback is _not_ called if zero
                  // `feeData` is provided. If `feeData` is provided, we assume
                  // the fee recipient is a contract that implements the
                  // `IFeeRecipient` interface.
                  if (fee.feeData.length > 0) {
                      // Invoke the callback
                      bytes4 callbackResult = IFeeRecipient(fee.recipient).receiveZeroExFeeCallback(
                          useNativeToken ? NATIVE_TOKEN_ADDRESS : address(order.erc20Token),
                          feeFillAmount,
                          fee.feeData
                      );
                      // Check for the magic success bytes
                      require(
                          callbackResult == FEE_CALLBACK_MAGIC_BYTES,
                          "NFTOrders::_payFees/CALLBACK_FAILED"
                      );
                  }
                  // Sum the fees paid
                  totalFeesPaid = totalFeesPaid.safeAdd(feeFillAmount);
              }
          }
          /// @dev If the given order is buying an NFT asset, checks
          ///      whether or not the given token ID satisfies the required
          ///      properties specified in the order. If the order does not
          ///      specify any properties, this function instead checks
          ///      whether the given token ID matches the ID in the order.
          ///      Reverts if any checks fail, or if the order is selling
          ///      an NFT asset.
          /// @param order The NFT order.
          /// @param tokenId The ID of the NFT asset.
          function _validateOrderProperties(
              LibNFTOrder.NFTOrder memory order,
              uint256 tokenId
          )
              internal
              view
          {
              // Order must be buying an NFT asset to have properties.
              require(
                  order.direction == LibNFTOrder.TradeDirection.BUY_NFT,
                  "NFTOrders::_validateOrderProperties/WRONG_TRADE_DIRECTION"
              );
              // If no properties are specified, check that the given
              // `tokenId` matches the one specified in the order.
              if (order.nftProperties.length == 0) {
                  if (tokenId != order.nftId) {
                      LibNFTOrdersRichErrors.TokenIdMismatchError(
                          tokenId,
                          order.nftId
                      ).rrevert();
                  }
              } else {
                  // Validate each property
                  for (uint256 i = 0; i < order.nftProperties.length; i++) {
                      LibNFTOrder.Property memory property = order.nftProperties[i];
                      // `address(0)` is interpreted as a no-op. Any token ID
                      // will satisfy a property with `propertyValidator == address(0)`.
                      if (address(property.propertyValidator) == address(0)) {
                          continue;
                      }
                      // Call the property validator and throw a descriptive error
                      // if the call reverts.
                      try property.propertyValidator.validateProperty(
                          order.nft,
                          tokenId,
                          property.propertyData
                      ) {} catch (bytes memory errorData) {
                          LibNFTOrdersRichErrors.PropertyValidationFailedError(
                              address(property.propertyValidator),
                              order.nft,
                              tokenId,
                              property.propertyData,
                              errorData
                          ).rrevert();
                      }
                  }
              }
          }
          /// @dev Validates that the given signature is valid for the
          ///      given maker and order hash. Reverts if the signature
          ///      is not valid.
          /// @param orderHash The hash of the order that was signed.
          /// @param signature The signature to check.
          /// @param maker The maker of the order.
          function _validateOrderSignature(
              bytes32 orderHash,
              LibSignature.Signature memory signature,
              address maker
          )
              internal
              virtual
              view;
          /// @dev Transfers an NFT asset.
          /// @param token The address of the NFT contract.
          /// @param from The address currently holding the asset.
          /// @param to The address to transfer the asset to.
          /// @param tokenId The ID of the asset to transfer.
          /// @param amount The amount of the asset to transfer. Always
          ///        1 for ERC721 assets.
          function _transferNFTAssetFrom(
              address token,
              address from,
              address to,
              uint256 tokenId,
              uint256 amount
          )
              internal
              virtual;
          /// @dev Updates storage to indicate that the given order
          ///      has been filled by the given amount.
          /// @param order The order that has been filled.
          /// @param orderHash The hash of `order`.
          /// @param fillAmount The amount (denominated in the NFT asset)
          ///        that the order has been filled by.
          function _updateOrderState(
              LibNFTOrder.NFTOrder memory order,
              bytes32 orderHash,
              uint128 fillAmount
          )
              internal
              virtual;
          /// @dev Get the order info for an NFT order.
          /// @param order The NFT order.
          /// @return orderInfo Info about the order.
          function _getOrderInfo(LibNFTOrder.NFTOrder memory order)
              internal
              virtual
              view
              returns (LibNFTOrder.OrderInfo memory orderInfo);
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2019 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      import "./LibSafeMathV06.sol";
      import "./errors/LibRichErrorsV06.sol";
      import "./errors/LibMathRichErrorsV06.sol";
      library LibMathV06 {
          using LibSafeMathV06 for uint256;
          /// @dev Calculates partial value given a numerator and denominator rounded down.
          ///      Reverts if rounding error is >= 0.1%
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to calculate partial of.
          /// @return partialAmount Partial value of target rounded down.
          function safeGetPartialAmountFloor(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (uint256 partialAmount)
          {
              if (isRoundingErrorFloor(
                      numerator,
                      denominator,
                      target
              )) {
                  LibRichErrorsV06.rrevert(LibMathRichErrorsV06.RoundingError(
                      numerator,
                      denominator,
                      target
                  ));
              }
              partialAmount = numerator.safeMul(target).safeDiv(denominator);
              return partialAmount;
          }
          /// @dev Calculates partial value given a numerator and denominator rounded down.
          ///      Reverts if rounding error is >= 0.1%
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to calculate partial of.
          /// @return partialAmount Partial value of target rounded up.
          function safeGetPartialAmountCeil(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (uint256 partialAmount)
          {
              if (isRoundingErrorCeil(
                      numerator,
                      denominator,
                      target
              )) {
                  LibRichErrorsV06.rrevert(LibMathRichErrorsV06.RoundingError(
                      numerator,
                      denominator,
                      target
                  ));
              }
              // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
              //       ceil(a / b) = floor((a + b - 1) / b)
              // To implement `ceil(a / b)` using safeDiv.
              partialAmount = numerator.safeMul(target)
                  .safeAdd(denominator.safeSub(1))
                  .safeDiv(denominator);
              return partialAmount;
          }
          /// @dev Calculates partial value given a numerator and denominator rounded down.
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to calculate partial of.
          /// @return partialAmount Partial value of target rounded down.
          function getPartialAmountFloor(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (uint256 partialAmount)
          {
              partialAmount = numerator.safeMul(target).safeDiv(denominator);
              return partialAmount;
          }
          /// @dev Calculates partial value given a numerator and denominator rounded down.
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to calculate partial of.
          /// @return partialAmount Partial value of target rounded up.
          function getPartialAmountCeil(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (uint256 partialAmount)
          {
              // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
              //       ceil(a / b) = floor((a + b - 1) / b)
              // To implement `ceil(a / b)` using safeDiv.
              partialAmount = numerator.safeMul(target)
                  .safeAdd(denominator.safeSub(1))
                  .safeDiv(denominator);
              return partialAmount;
          }
          /// @dev Checks if rounding error >= 0.1% when rounding down.
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to multiply with numerator/denominator.
          /// @return isError Rounding error is present.
          function isRoundingErrorFloor(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (bool isError)
          {
              if (denominator == 0) {
                  LibRichErrorsV06.rrevert(LibMathRichErrorsV06.DivisionByZeroError());
              }
              // The absolute rounding error is the difference between the rounded
              // value and the ideal value. The relative rounding error is the
              // absolute rounding error divided by the absolute value of the
              // ideal value. This is undefined when the ideal value is zero.
              //
              // The ideal value is `numerator * target / denominator`.
              // Let's call `numerator * target % denominator` the remainder.
              // The absolute error is `remainder / denominator`.
              //
              // When the ideal value is zero, we require the absolute error to
              // be zero. Fortunately, this is always the case. The ideal value is
              // zero iff `numerator == 0` and/or `target == 0`. In this case the
              // remainder and absolute error are also zero.
              if (target == 0 || numerator == 0) {
                  return false;
              }
              // Otherwise, we want the relative rounding error to be strictly
              // less than 0.1%.
              // The relative error is `remainder / (numerator * target)`.
              // We want the relative error less than 1 / 1000:
              //        remainder / (numerator * denominator)  <  1 / 1000
              // or equivalently:
              //        1000 * remainder  <  numerator * target
              // so we have a rounding error iff:
              //        1000 * remainder  >=  numerator * target
              uint256 remainder = mulmod(
                  target,
                  numerator,
                  denominator
              );
              isError = remainder.safeMul(1000) >= numerator.safeMul(target);
              return isError;
          }
          /// @dev Checks if rounding error >= 0.1% when rounding up.
          /// @param numerator Numerator.
          /// @param denominator Denominator.
          /// @param target Value to multiply with numerator/denominator.
          /// @return isError Rounding error is present.
          function isRoundingErrorCeil(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (bool isError)
          {
              if (denominator == 0) {
                  LibRichErrorsV06.rrevert(LibMathRichErrorsV06.DivisionByZeroError());
              }
              // See the comments in `isRoundingError`.
              if (target == 0 || numerator == 0) {
                  // When either is zero, the ideal value and rounded value are zero
                  // and there is no rounding error. (Although the relative error
                  // is undefined.)
                  return false;
              }
              // Compute remainder as before
              uint256 remainder = mulmod(
                  target,
                  numerator,
                  denominator
              );
              remainder = denominator.safeSub(remainder) % denominator;
              isError = remainder.safeMul(1000) >= numerator.safeMul(target);
              return isError;
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibMathRichErrorsV06 {
          // bytes4(keccak256("DivisionByZeroError()"))
          bytes internal constant DIVISION_BY_ZERO_ERROR =
              hex"a791837c";
          // bytes4(keccak256("RoundingError(uint256,uint256,uint256)"))
          bytes4 internal constant ROUNDING_ERROR_SELECTOR =
              0x339f3de2;
          // solhint-disable func-name-mixedcase
          function DivisionByZeroError()
              internal
              pure
              returns (bytes memory)
          {
              return DIVISION_BY_ZERO_ERROR;
          }
          function RoundingError(
              uint256 numerator,
              uint256 denominator,
              uint256 target
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  ROUNDING_ERROR_SELECTOR,
                  numerator,
                  denominator,
                  target
              );
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2021 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibNFTOrdersRichErrors {
          // solhint-disable func-name-mixedcase
          function OverspentEthError(
              uint256 ethSpent,
              uint256 ethAvailable
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("OverspentEthError(uint256,uint256)")),
                  ethSpent,
                  ethAvailable
              );
          }
          function InsufficientEthError(
              uint256 ethAvailable,
              uint256 orderAmount
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("InsufficientEthError(uint256,uint256)")),
                  ethAvailable,
                  orderAmount
              );
          }
          function ERC721TokenMismatchError(
              address token1,
              address token2
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("ERC721TokenMismatchError(address,address)")),
                  token1,
                  token2
              );
          }
          function ERC1155TokenMismatchError(
              address token1,
              address token2
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("ERC1155TokenMismatchError(address,address)")),
                  token1,
                  token2
              );
          }
          function ERC20TokenMismatchError(
              address token1,
              address token2
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("ERC20TokenMismatchError(address,address)")),
                  token1,
                  token2
              );
          }
          function NegativeSpreadError(
              uint256 sellOrderAmount,
              uint256 buyOrderAmount
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("NegativeSpreadError(uint256,uint256)")),
                  sellOrderAmount,
                  buyOrderAmount
              );
          }
          function SellOrderFeesExceedSpreadError(
              uint256 sellOrderFees,
              uint256 spread
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("SellOrderFeesExceedSpreadError(uint256,uint256)")),
                  sellOrderFees,
                  spread
              );
          }
          function OnlyTakerError(
              address sender,
              address taker
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("OnlyTakerError(address,address)")),
                  sender,
                  taker
              );
          }
          function InvalidSignerError(
              address maker,
              address signer
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("InvalidSignerError(address,address)")),
                  maker,
                  signer
              );
          }
          function OrderNotFillableError(
              address maker,
              uint256 nonce,
              uint8 orderStatus
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("OrderNotFillableError(address,uint256,uint8)")),
                  maker,
                  nonce,
                  orderStatus
              );
          }
          function TokenIdMismatchError(
              uint256 tokenId,
              uint256 orderTokenId
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("TokenIdMismatchError(uint256,uint256)")),
                  tokenId,
                  orderTokenId
              );
          }
          function PropertyValidationFailedError(
              address propertyValidator,
              address token,
              uint256 tokenId,
              bytes memory propertyData,
              bytes memory errorData
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("PropertyValidationFailedError(address,address,uint256,bytes,bytes)")),
                  propertyValidator,
                  token,
                  tokenId,
                  propertyData,
                  errorData
              );
          }
          function ExceedsRemainingOrderAmount(
              uint128 remainingOrderAmount,
              uint128 fillAmount
          )
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("ExceedsRemainingOrderAmount(uint128,uint128)")),
                  remainingOrderAmount,
                  fillAmount
              );
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "../errors/LibCommonRichErrors.sol";
      import "../errors/LibOwnableRichErrors.sol";
      import "../features/interfaces/IOwnableFeature.sol";
      import "../features/interfaces/ISimpleFunctionRegistryFeature.sol";
      /// @dev Common feature utilities.
      abstract contract FixinCommon {
          using LibRichErrorsV06 for bytes;
          /// @dev The implementation address of this feature.
          address internal immutable _implementation;
          /// @dev The caller must be this contract.
          modifier onlySelf() virtual {
              if (msg.sender != address(this)) {
                  LibCommonRichErrors.OnlyCallableBySelfError(msg.sender).rrevert();
              }
              _;
          }
          /// @dev The caller of this function must be the owner.
          modifier onlyOwner() virtual {
              {
                  address owner = IOwnableFeature(address(this)).owner();
                  if (msg.sender != owner) {
                      LibOwnableRichErrors.OnlyOwnerError(
                          msg.sender,
                          owner
                      ).rrevert();
                  }
              }
              _;
          }
          constructor() internal {
              // Remember this feature's original address.
              _implementation = address(this);
          }
          /// @dev Registers a function implemented by this feature at `_implementation`.
          ///      Can and should only be called within a `migrate()`.
          /// @param selector The selector of the function whose implementation
          ///        is at `_implementation`.
          function _registerFeatureFunction(bytes4 selector)
              internal
          {
              ISimpleFunctionRegistryFeature(address(this)).extend(selector, _implementation);
          }
          /// @dev Encode a feature version as a `uint256`.
          /// @param major The major version number of the feature.
          /// @param minor The minor version number of the feature.
          /// @param revision The revision number of the feature.
          /// @return encodedVersion The encoded version number.
          function _encodeVersion(uint32 major, uint32 minor, uint32 revision)
              internal
              pure
              returns (uint256 encodedVersion)
          {
              return (uint256(major) << 64) | (uint256(minor) << 32) | uint256(revision);
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      library LibCommonRichErrors {
          // solhint-disable func-name-mixedcase
          function OnlyCallableBySelfError(address sender)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("OnlyCallableBySelfError(address)")),
                  sender
              );
          }
          function IllegalReentrancyError(bytes4 selector, uint256 reentrancyFlags)
              internal
              pure
              returns (bytes memory)
          {
              return abi.encodeWithSelector(
                  bytes4(keccak256("IllegalReentrancyError(bytes4,uint256)")),
                  selector,
                  reentrancyFlags
              );
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/interfaces/IOwnableV06.sol";
      // solhint-disable no-empty-blocks
      /// @dev Owner management and migration features.
      interface IOwnableFeature is
          IOwnableV06
      {
          /// @dev Emitted when `migrate()` is called.
          /// @param caller The caller of `migrate()`.
          /// @param migrator The migration contract.
          /// @param newOwner The address of the new owner.
          event Migrated(address caller, address migrator, address newOwner);
          /// @dev Execute a migration function in the context of the ZeroEx contract.
          ///      The result of the function being called should be the magic bytes
          ///      0x2c64c5ef (`keccack('MIGRATE_SUCCESS')`). Only callable by the owner.
          ///      The owner will be temporarily set to `address(this)` inside the call.
          ///      Before returning, the owner will be set to `newOwner`.
          /// @param target The migrator contract address.
          /// @param newOwner The address of the new owner.
          /// @param data The call data.
          function migrate(address target, bytes calldata data, address newOwner) external;
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      interface IOwnableV06 {
          /// @dev Emitted by Ownable when ownership is transferred.
          /// @param previousOwner The previous owner of the contract.
          /// @param newOwner The new owner of the contract.
          event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
          /// @dev Transfers ownership of the contract to a new address.
          /// @param newOwner The address that will become the owner.
          function transferOwnership(address newOwner) external;
          /// @dev The owner of this contract.
          /// @return ownerAddress The owner address.
          function owner() external view returns (address ownerAddress);
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      /// @dev Basic registry management features.
      interface ISimpleFunctionRegistryFeature {
          /// @dev A function implementation was updated via `extend()` or `rollback()`.
          /// @param selector The function selector.
          /// @param oldImpl The implementation contract address being replaced.
          /// @param newImpl The replacement implementation contract address.
          event ProxyFunctionUpdated(bytes4 indexed selector, address oldImpl, address newImpl);
          /// @dev Roll back to a prior implementation of a function.
          /// @param selector The function selector.
          /// @param targetImpl The address of an older implementation of the function.
          function rollback(bytes4 selector, address targetImpl) external;
          /// @dev Register or replace a function.
          /// @param selector The function selector.
          /// @param impl The implementation contract for the function.
          function extend(bytes4 selector, address impl) external;
          /// @dev Retrieve the length of the rollback history for a function.
          /// @param selector The function selector.
          /// @return rollbackLength The number of items in the rollback history for
          ///         the function.
          function getRollbackLength(bytes4 selector)
              external
              view
              returns (uint256 rollbackLength);
          /// @dev Retrieve an entry in the rollback history for a function.
          /// @param selector The function selector.
          /// @param idx The index in the rollback history.
          /// @return impl An implementation address for the function at
          ///         index `idx`.
          function getRollbackEntryAtIndex(bytes4 selector, uint256 idx)
              external
              view
              returns (address impl);
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
      import "../errors/LibCommonRichErrors.sol";
      import "../errors/LibOwnableRichErrors.sol";
      /// @dev EIP712 helpers for features.
      abstract contract FixinEIP712 {
          /// @dev The domain hash separator for the entire exchange proxy.
          bytes32 public immutable EIP712_DOMAIN_SEPARATOR;
          constructor(address zeroExAddress) internal {
              // Compute `EIP712_DOMAIN_SEPARATOR`
              {
                  uint256 chainId;
                  assembly { chainId := chainid() }
                  EIP712_DOMAIN_SEPARATOR = keccak256(
                      abi.encode(
                          keccak256(
                              "EIP712Domain("
                                  "string name,"
                                  "string version,"
                                  "uint256 chainId,"
                                  "address verifyingContract"
                              ")"
                          ),
                          keccak256("ZeroEx"),
                          keccak256("1.0.0"),
                          chainId,
                          zeroExAddress
                      )
                  );
              }
          }
          function _getEIP712Hash(bytes32 structHash)
              internal
              view
              returns (bytes32 eip712Hash)
          {
              return keccak256(abi.encodePacked(
                  hex"1901",
                  EIP712_DOMAIN_SEPARATOR,
                  structHash
              ));
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2020 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6.5;
      pragma experimental ABIEncoderV2;
      import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
      import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
      /// @dev Helpers for moving tokens around.
      abstract contract FixinTokenSpender {
          // Mask of the lower 20 bytes of a bytes32.
          uint256 constant private ADDRESS_MASK = 0x000000000000000000000000ffffffffffffffffffffffffffffffffffffffff;
          /// @dev Transfers ERC20 tokens from `owner` to `to`.
          /// @param token The token to spend.
          /// @param owner The owner of the tokens.
          /// @param to The recipient of the tokens.
          /// @param amount The amount of `token` to transfer.
          function _transferERC20TokensFrom(
              IERC20TokenV06 token,
              address owner,
              address to,
              uint256 amount
          )
              internal
          {
              require(address(token) != address(this), "FixinTokenSpender/CANNOT_INVOKE_SELF");
              assembly {
                  let ptr := mload(0x40) // free memory pointer
                  // selector for transferFrom(address,address,uint256)
                  mstore(ptr, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
                  mstore(add(ptr, 0x04), and(owner, ADDRESS_MASK))
                  mstore(add(ptr, 0x24), and(to, ADDRESS_MASK))
                  mstore(add(ptr, 0x44), amount)
                  let success := call(
                      gas(),
                      and(token, ADDRESS_MASK),
                      0,
                      ptr,
                      0x64,
                      ptr,
                      32
                  )
                  let rdsize := returndatasize()
                  // Check for ERC20 success. ERC20 tokens should return a boolean,
                  // but some don't. We accept 0-length return data as success, or at
                  // least 32 bytes that starts with a 32-byte boolean true.
                  success := and(
                      success,                             // call itself succeeded
                      or(
                          iszero(rdsize),                  // no return data, or
                          and(
                              iszero(lt(rdsize, 32)),      // at least 32 bytes
                              eq(mload(ptr), 1)            // starts with uint256(1)
                          )
                      )
                  )
                  if iszero(success) {
                      returndatacopy(ptr, 0, rdsize)
                      revert(ptr, rdsize)
                  }
              }
          }
          /// @dev Transfers ERC20 tokens from ourselves to `to`.
          /// @param token The token to spend.
          /// @param to The recipient of the tokens.
          /// @param amount The amount of `token` to transfer.
          function _transferERC20Tokens(
              IERC20TokenV06 token,
              address to,
              uint256 amount
          )
              internal
          {
              require(address(token) != address(this), "FixinTokenSpender/CANNOT_INVOKE_SELF");
              assembly {
                  let ptr := mload(0x40) // free memory pointer
                  // selector for transfer(address,uint256)
                  mstore(ptr, 0xa9059cbb00000000000000000000000000000000000000000000000000000000)
                  mstore(add(ptr, 0x04), and(to, ADDRESS_MASK))
                  mstore(add(ptr, 0x24), amount)
                  let success := call(
                      gas(),
                      and(token, ADDRESS_MASK),
                      0,
                      ptr,
                      0x44,
                      ptr,
                      32
                  )
                  let rdsize := returndatasize()
                  // Check for ERC20 success. ERC20 tokens should return a boolean,
                  // but some don't. We accept 0-length return data as success, or at
                  // least 32 bytes that starts with a 32-byte boolean true.
                  success := and(
                      success,                             // call itself succeeded
                      or(
                          iszero(rdsize),                  // no return data, or
                          and(
                              iszero(lt(rdsize, 32)),      // at least 32 bytes
                              eq(mload(ptr), 1)            // starts with uint256(1)
                          )
                      )
                  )
                  if iszero(success) {
                      returndatacopy(ptr, 0, rdsize)
                      revert(ptr, rdsize)
                  }
              }
          }
          /// @dev Transfers some amount of ETH to the given recipient and
          ///      reverts if the transfer fails.
          /// @param recipient The recipient of the ETH.
          /// @param amount The amount of ETH to transfer.
          function _transferEth(address payable recipient, uint256 amount)
              internal
          {
              if (amount > 0) {
                  (bool success,) = recipient.call{value: amount}("");
                  require(success, "FixinTokenSpender::_transferEth/TRANSFER_FAILED");
              }
          }
          /// @dev Gets the maximum amount of an ERC20 token `token` that can be
          ///      pulled from `owner` by this address.
          /// @param token The token to spend.
          /// @param owner The owner of the tokens.
          /// @return amount The amount of tokens that can be pulled.
          function _getSpendableERC20BalanceOf(
              IERC20TokenV06 token,
              address owner
          )
              internal
              view
              returns (uint256)
          {
              return LibSafeMathV06.min256(
                  token.allowance(owner, address(this)),
                  token.balanceOf(owner)
              );
          }
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2021 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      pragma experimental ABIEncoderV2;
      interface IFeeRecipient {
          /// @dev A callback function invoked in the ERC721Feature for each ERC721
          ///      order fee that get paid. Integrators can make use of this callback
          ///      to implement arbitrary fee-handling logic, e.g. splitting the fee
          ///      between multiple parties.
          /// @param tokenAddress The address of the token in which the received fee is
          ///        denominated. `0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE` indicates
          ///        that the fee was paid in the native token (e.g. ETH).
          /// @param amount The amount of the given token received.
          /// @param feeData Arbitrary data encoded in the `Fee` used by this callback.
          /// @return success The selector of this function (0x0190805e),
          ///         indicating that the callback succeeded.
          function receiveZeroExFeeCallback(
              address tokenAddress,
              uint256 amount,
              bytes calldata feeData
          )
              external
              returns (bytes4 success);
      }
      // SPDX-License-Identifier: Apache-2.0
      /*
        Copyright 2021 ZeroEx Intl.
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
          http://www.apache.org/licenses/LICENSE-2.0
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
      */
      pragma solidity ^0.6;
      pragma experimental ABIEncoderV2;
      interface ITakerCallback {
          /// @dev A taker callback function invoked in ERC721OrdersFeature and
          ///      ERC1155OrdersFeature between the maker -> taker transfer and
          ///      the taker -> maker transfer.
          /// @param orderHash The hash of the order being filled when this
          ///        callback is invoked.
          /// @param callbackData Arbitrary data used by this callback.
          /// @return success The selector of this function,
          ///         indicating that the callback succeeded.
          function zeroExTakerCallback(
              bytes32 orderHash,
              bytes calldata callbackData
          )
              external
              returns (bytes4 success);
      }