ETH Price: $2,508.00 (-1.56%)

Transaction Decoder

Block:
19522794 at Mar-27-2024 02:41:23 AM +UTC
Transaction Fee:
0.001513834659457911 ETH $3.80
Gas Used:
72,513 Gas / 20.876734647 Gwei

Emitted Events:

381 GnosisSafeProxy.0x3d0ce9bfc3ed7d6862dbb28b2dea94561fe714a1b4d019aa8af39730d1ad7c3d( 0x3d0ce9bfc3ed7d6862dbb28b2dea94561fe714a1b4d019aa8af39730d1ad7c3d, 0x000000000000000000000000830bd73e4184cef73443c15111a1df14e495c706, 000000000000000000000000000000000000000000000000498d61eb5d920000 )
382 NounsAuctionHouseProxy.0x1159164c56f277e6fc99c11731bd380e0347deb969b75523398734c252706ea3( 0x1159164c56f277e6fc99c11731bd380e0347deb969b75523398734c252706ea3, 0x0000000000000000000000000000000000000000000000000000000000000422, 000000000000000000000000be8ee3411faf81ca93fe5b3f1cc2d26629acdb04, 0000000000000000000000000000000000000000000000004e8c5c0314b60000, 0000000000000000000000000000000000000000000000000000000000000000 )

Account State Difference:

  Address   Before After State Difference Code
0x830BD73E...4e495C706
(Nouns DAO: Nouns Auction House Proxy)
5.3 Eth5.66 Eth0.36
0x90dD9d99...B41cfd222 15.609852117203005917 Eth20.909852117203005917 Eth5.3
(beaverbuild)
18.458089098459049636 Eth18.458093445617895442 Eth0.000004347158845806
0xbE8eE341...629acDB04
10.383918764139431337 Eth
Nonce: 78
4.722404929479973426 Eth
Nonce: 79
5.661513834659457911

Execution Trace

ETH 5.66 NounsAuctionHouseProxy.659dd2b4( )
  • ETH 5.66 NounsAuctionHouse.createBid( nounId=1058 )
    • ETH 5.3 GnosisSafeProxy.CALL( )
      • ETH 5.3 GnosisSafe.DELEGATECALL( )
        File 1 of 4: NounsAuctionHouseProxy
        // SPDX-License-Identifier: GPL-3.0
        /// @title The Nouns DAO auction house proxy
        /*********************************
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
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         * ░░░░░░█████████░░█████████░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         *********************************/
        pragma solidity ^0.8.6;
        import { TransparentUpgradeableProxy } from '@openzeppelin/contracts/proxy/transparent/TransparentUpgradeableProxy.sol';
        contract NounsAuctionHouseProxy is TransparentUpgradeableProxy {
            constructor(
                address logic,
                address admin,
                bytes memory data
            ) TransparentUpgradeableProxy(logic, admin, data) {}
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        import "../ERC1967/ERC1967Proxy.sol";
        /**
         * @dev This contract implements a proxy that is upgradeable by an admin.
         *
         * To avoid https://medium.com/nomic-labs-blog/malicious-backdoors-in-ethereum-proxies-62629adf3357[proxy selector
         * clashing], which can potentially be used in an attack, this contract uses the
         * https://blog.openzeppelin.com/the-transparent-proxy-pattern/[transparent proxy pattern]. This pattern implies two
         * things that go hand in hand:
         *
         * 1. If any account other than the admin calls the proxy, the call will be forwarded to the implementation, even if
         * that call matches one of the admin functions exposed by the proxy itself.
         * 2. If the admin calls the proxy, it can access the admin functions, but its calls will never be forwarded to the
         * implementation. If the admin tries to call a function on the implementation it will fail with an error that says
         * "admin cannot fallback to proxy target".
         *
         * These properties mean that the admin account can only be used for admin actions like upgrading the proxy or changing
         * the admin, so it's best if it's a dedicated account that is not used for anything else. This will avoid headaches due
         * to sudden errors when trying to call a function from the proxy implementation.
         *
         * Our recommendation is for the dedicated account to be an instance of the {ProxyAdmin} contract. If set up this way,
         * you should think of the `ProxyAdmin` instance as the real administrative interface of your proxy.
         */
        contract TransparentUpgradeableProxy is ERC1967Proxy {
            /**
             * @dev Initializes an upgradeable proxy managed by `_admin`, backed by the implementation at `_logic`, and
             * optionally initialized with `_data` as explained in {ERC1967Proxy-constructor}.
             */
            constructor(
                address _logic,
                address admin_,
                bytes memory _data
            ) payable ERC1967Proxy(_logic, _data) {
                assert(_ADMIN_SLOT == bytes32(uint256(keccak256("eip1967.proxy.admin")) - 1));
                _changeAdmin(admin_);
            }
            /**
             * @dev Modifier used internally that will delegate the call to the implementation unless the sender is the admin.
             */
            modifier ifAdmin() {
                if (msg.sender == _getAdmin()) {
                    _;
                } else {
                    _fallback();
                }
            }
            /**
             * @dev Returns the current admin.
             *
             * NOTE: Only the admin can call this function. See {ProxyAdmin-getProxyAdmin}.
             *
             * TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
             * https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
             * `0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103`
             */
            function admin() external ifAdmin returns (address admin_) {
                admin_ = _getAdmin();
            }
            /**
             * @dev Returns the current implementation.
             *
             * NOTE: Only the admin can call this function. See {ProxyAdmin-getProxyImplementation}.
             *
             * TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
             * https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
             * `0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc`
             */
            function implementation() external ifAdmin returns (address implementation_) {
                implementation_ = _implementation();
            }
            /**
             * @dev Changes the admin of the proxy.
             *
             * Emits an {AdminChanged} event.
             *
             * NOTE: Only the admin can call this function. See {ProxyAdmin-changeProxyAdmin}.
             */
            function changeAdmin(address newAdmin) external virtual ifAdmin {
                _changeAdmin(newAdmin);
            }
            /**
             * @dev Upgrade the implementation of the proxy.
             *
             * NOTE: Only the admin can call this function. See {ProxyAdmin-upgrade}.
             */
            function upgradeTo(address newImplementation) external ifAdmin {
                _upgradeToAndCall(newImplementation, bytes(""), false);
            }
            /**
             * @dev Upgrade the implementation of the proxy, and then call a function from the new implementation as specified
             * by `data`, which should be an encoded function call. This is useful to initialize new storage variables in the
             * proxied contract.
             *
             * NOTE: Only the admin can call this function. See {ProxyAdmin-upgradeAndCall}.
             */
            function upgradeToAndCall(address newImplementation, bytes calldata data) external payable ifAdmin {
                _upgradeToAndCall(newImplementation, data, true);
            }
            /**
             * @dev Returns the current admin.
             */
            function _admin() internal view virtual returns (address) {
                return _getAdmin();
            }
            /**
             * @dev Makes sure the admin cannot access the fallback function. See {Proxy-_beforeFallback}.
             */
            function _beforeFallback() internal virtual override {
                require(msg.sender != _getAdmin(), "TransparentUpgradeableProxy: admin cannot fallback to proxy target");
                super._beforeFallback();
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        import "../Proxy.sol";
        import "./ERC1967Upgrade.sol";
        /**
         * @dev This contract implements an upgradeable proxy. It is upgradeable because calls are delegated to an
         * implementation address that can be changed. This address is stored in storage in the location specified by
         * https://eips.ethereum.org/EIPS/eip-1967[EIP1967], so that it doesn't conflict with the storage layout of the
         * implementation behind the proxy.
         */
        contract ERC1967Proxy is Proxy, ERC1967Upgrade {
            /**
             * @dev Initializes the upgradeable proxy with an initial implementation specified by `_logic`.
             *
             * If `_data` is nonempty, it's used as data in a delegate call to `_logic`. This will typically be an encoded
             * function call, and allows initializating the storage of the proxy like a Solidity constructor.
             */
            constructor(address _logic, bytes memory _data) payable {
                assert(_IMPLEMENTATION_SLOT == bytes32(uint256(keccak256("eip1967.proxy.implementation")) - 1));
                _upgradeToAndCall(_logic, _data, false);
            }
            /**
             * @dev Returns the current implementation address.
             */
            function _implementation() internal view virtual override returns (address impl) {
                return ERC1967Upgrade._getImplementation();
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        /**
         * @dev This abstract contract provides a fallback function that delegates all calls to another contract using the EVM
         * instruction `delegatecall`. We refer to the second contract as the _implementation_ behind the proxy, and it has to
         * be specified by overriding the virtual {_implementation} function.
         *
         * Additionally, delegation to the implementation can be triggered manually through the {_fallback} function, or to a
         * different contract through the {_delegate} function.
         *
         * The success and return data of the delegated call will be returned back to the caller of the proxy.
         */
        abstract contract Proxy {
            /**
             * @dev Delegates the current call to `implementation`.
             *
             * This function does not return to its internall call site, it will return directly to the external caller.
             */
            function _delegate(address implementation) internal virtual {
                assembly {
                    // Copy msg.data. We take full control of memory in this inline assembly
                    // block because it will not return to Solidity code. We overwrite the
                    // Solidity scratch pad at memory position 0.
                    calldatacopy(0, 0, calldatasize())
                    // Call the implementation.
                    // out and outsize are 0 because we don't know the size yet.
                    let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
                    // Copy the returned data.
                    returndatacopy(0, 0, returndatasize())
                    switch result
                    // delegatecall returns 0 on error.
                    case 0 {
                        revert(0, returndatasize())
                    }
                    default {
                        return(0, returndatasize())
                    }
                }
            }
            /**
             * @dev This is a virtual function that should be overriden so it returns the address to which the fallback function
             * and {_fallback} should delegate.
             */
            function _implementation() internal view virtual returns (address);
            /**
             * @dev Delegates the current call to the address returned by `_implementation()`.
             *
             * This function does not return to its internall call site, it will return directly to the external caller.
             */
            function _fallback() internal virtual {
                _beforeFallback();
                _delegate(_implementation());
            }
            /**
             * @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if no other
             * function in the contract matches the call data.
             */
            fallback() external payable virtual {
                _fallback();
            }
            /**
             * @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if call data
             * is empty.
             */
            receive() external payable virtual {
                _fallback();
            }
            /**
             * @dev Hook that is called before falling back to the implementation. Can happen as part of a manual `_fallback`
             * call, or as part of the Solidity `fallback` or `receive` functions.
             *
             * If overriden should call `super._beforeFallback()`.
             */
            function _beforeFallback() internal virtual {}
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.2;
        import "../beacon/IBeacon.sol";
        import "../../utils/Address.sol";
        import "../../utils/StorageSlot.sol";
        /**
         * @dev This abstract contract provides getters and event emitting update functions for
         * https://eips.ethereum.org/EIPS/eip-1967[EIP1967] slots.
         *
         * _Available since v4.1._
         *
         * @custom:oz-upgrades-unsafe-allow delegatecall
         */
        abstract contract ERC1967Upgrade {
            // This is the keccak-256 hash of "eip1967.proxy.rollback" subtracted by 1
            bytes32 private constant _ROLLBACK_SLOT = 0x4910fdfa16fed3260ed0e7147f7cc6da11a60208b5b9406d12a635614ffd9143;
            /**
             * @dev Storage slot with the address of the current implementation.
             * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
             * validated in the constructor.
             */
            bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
            /**
             * @dev Emitted when the implementation is upgraded.
             */
            event Upgraded(address indexed implementation);
            /**
             * @dev Returns the current implementation address.
             */
            function _getImplementation() internal view returns (address) {
                return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
            }
            /**
             * @dev Stores a new address in the EIP1967 implementation slot.
             */
            function _setImplementation(address newImplementation) private {
                require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
                StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
            }
            /**
             * @dev Perform implementation upgrade
             *
             * Emits an {Upgraded} event.
             */
            function _upgradeTo(address newImplementation) internal {
                _setImplementation(newImplementation);
                emit Upgraded(newImplementation);
            }
            /**
             * @dev Perform implementation upgrade with additional setup call.
             *
             * Emits an {Upgraded} event.
             */
            function _upgradeToAndCall(
                address newImplementation,
                bytes memory data,
                bool forceCall
            ) internal {
                _upgradeTo(newImplementation);
                if (data.length > 0 || forceCall) {
                    Address.functionDelegateCall(newImplementation, data);
                }
            }
            /**
             * @dev Perform implementation upgrade with security checks for UUPS proxies, and additional setup call.
             *
             * Emits an {Upgraded} event.
             */
            function _upgradeToAndCallSecure(
                address newImplementation,
                bytes memory data,
                bool forceCall
            ) internal {
                address oldImplementation = _getImplementation();
                // Initial upgrade and setup call
                _setImplementation(newImplementation);
                if (data.length > 0 || forceCall) {
                    Address.functionDelegateCall(newImplementation, data);
                }
                // Perform rollback test if not already in progress
                StorageSlot.BooleanSlot storage rollbackTesting = StorageSlot.getBooleanSlot(_ROLLBACK_SLOT);
                if (!rollbackTesting.value) {
                    // Trigger rollback using upgradeTo from the new implementation
                    rollbackTesting.value = true;
                    Address.functionDelegateCall(
                        newImplementation,
                        abi.encodeWithSignature("upgradeTo(address)", oldImplementation)
                    );
                    rollbackTesting.value = false;
                    // Check rollback was effective
                    require(oldImplementation == _getImplementation(), "ERC1967Upgrade: upgrade breaks further upgrades");
                    // Finally reset to the new implementation and log the upgrade
                    _upgradeTo(newImplementation);
                }
            }
            /**
             * @dev Storage slot with the admin of the contract.
             * This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is
             * validated in the constructor.
             */
            bytes32 internal constant _ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;
            /**
             * @dev Emitted when the admin account has changed.
             */
            event AdminChanged(address previousAdmin, address newAdmin);
            /**
             * @dev Returns the current admin.
             */
            function _getAdmin() internal view returns (address) {
                return StorageSlot.getAddressSlot(_ADMIN_SLOT).value;
            }
            /**
             * @dev Stores a new address in the EIP1967 admin slot.
             */
            function _setAdmin(address newAdmin) private {
                require(newAdmin != address(0), "ERC1967: new admin is the zero address");
                StorageSlot.getAddressSlot(_ADMIN_SLOT).value = newAdmin;
            }
            /**
             * @dev Changes the admin of the proxy.
             *
             * Emits an {AdminChanged} event.
             */
            function _changeAdmin(address newAdmin) internal {
                emit AdminChanged(_getAdmin(), newAdmin);
                _setAdmin(newAdmin);
            }
            /**
             * @dev The storage slot of the UpgradeableBeacon contract which defines the implementation for this proxy.
             * This is bytes32(uint256(keccak256('eip1967.proxy.beacon')) - 1)) and is validated in the constructor.
             */
            bytes32 internal constant _BEACON_SLOT = 0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50;
            /**
             * @dev Emitted when the beacon is upgraded.
             */
            event BeaconUpgraded(address indexed beacon);
            /**
             * @dev Returns the current beacon.
             */
            function _getBeacon() internal view returns (address) {
                return StorageSlot.getAddressSlot(_BEACON_SLOT).value;
            }
            /**
             * @dev Stores a new beacon in the EIP1967 beacon slot.
             */
            function _setBeacon(address newBeacon) private {
                require(Address.isContract(newBeacon), "ERC1967: new beacon is not a contract");
                require(
                    Address.isContract(IBeacon(newBeacon).implementation()),
                    "ERC1967: beacon implementation is not a contract"
                );
                StorageSlot.getAddressSlot(_BEACON_SLOT).value = newBeacon;
            }
            /**
             * @dev Perform beacon upgrade with additional setup call. Note: This upgrades the address of the beacon, it does
             * not upgrade the implementation contained in the beacon (see {UpgradeableBeacon-_setImplementation} for that).
             *
             * Emits a {BeaconUpgraded} event.
             */
            function _upgradeBeaconToAndCall(
                address newBeacon,
                bytes memory data,
                bool forceCall
            ) internal {
                _setBeacon(newBeacon);
                emit BeaconUpgraded(newBeacon);
                if (data.length > 0 || forceCall) {
                    Address.functionDelegateCall(IBeacon(newBeacon).implementation(), data);
                }
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        /**
         * @dev This is the interface that {BeaconProxy} expects of its beacon.
         */
        interface IBeacon {
            /**
             * @dev Must return an address that can be used as a delegate call target.
             *
             * {BeaconProxy} will check that this address is a contract.
             */
            function implementation() external view returns (address);
        }
        // SPDX-License-Identifier: MIT
        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);
            }
            function _verifyCallResult(
                bool success,
                bytes memory returndata,
                string memory errorMessage
            ) private 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);
                    }
                }
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        /**
         * @dev Library for reading and writing primitive types to specific storage slots.
         *
         * Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.
         * This library helps with reading and writing to such slots without the need for inline assembly.
         *
         * The functions in this library return Slot structs that contain a `value` member that can be used to read or write.
         *
         * Example usage to set ERC1967 implementation slot:
         * ```
         * contract ERC1967 {
         *     bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
         *
         *     function _getImplementation() internal view returns (address) {
         *         return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
         *     }
         *
         *     function _setImplementation(address newImplementation) internal {
         *         require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
         *         StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
         *     }
         * }
         * ```
         *
         * _Available since v4.1 for `address`, `bool`, `bytes32`, and `uint256`._
         */
        library StorageSlot {
            struct AddressSlot {
                address value;
            }
            struct BooleanSlot {
                bool value;
            }
            struct Bytes32Slot {
                bytes32 value;
            }
            struct Uint256Slot {
                uint256 value;
            }
            /**
             * @dev Returns an `AddressSlot` with member `value` located at `slot`.
             */
            function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
                assembly {
                    r.slot := slot
                }
            }
            /**
             * @dev Returns an `BooleanSlot` with member `value` located at `slot`.
             */
            function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
                assembly {
                    r.slot := slot
                }
            }
            /**
             * @dev Returns an `Bytes32Slot` with member `value` located at `slot`.
             */
            function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
                assembly {
                    r.slot := slot
                }
            }
            /**
             * @dev Returns an `Uint256Slot` with member `value` located at `slot`.
             */
            function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
                assembly {
                    r.slot := slot
                }
            }
        }
        

        File 2 of 4: GnosisSafeProxy
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        
        /// @title IProxy - Helper interface to access masterCopy of the Proxy on-chain
        /// @author Richard Meissner - <[email protected]>
        interface IProxy {
            function masterCopy() external view returns (address);
        }
        
        /// @title GnosisSafeProxy - Generic proxy contract allows to execute all transactions applying the code of a master contract.
        /// @author Stefan George - <[email protected]>
        /// @author Richard Meissner - <[email protected]>
        contract GnosisSafeProxy {
            // singleton always needs to be first declared variable, to ensure that it is at the same location in the contracts to which calls are delegated.
            // To reduce deployment costs this variable is internal and needs to be retrieved via `getStorageAt`
            address internal singleton;
        
            /// @dev Constructor function sets address of singleton contract.
            /// @param _singleton Singleton address.
            constructor(address _singleton) {
                require(_singleton != address(0), "Invalid singleton address provided");
                singleton = _singleton;
            }
        
            /// @dev Fallback function forwards all transactions and returns all received return data.
            fallback() external payable {
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let _singleton := and(sload(0), 0xffffffffffffffffffffffffffffffffffffffff)
                    // 0xa619486e == keccak("masterCopy()"). The value is right padded to 32-bytes with 0s
                    if eq(calldataload(0), 0xa619486e00000000000000000000000000000000000000000000000000000000) {
                        mstore(0, _singleton)
                        return(0, 0x20)
                    }
                    calldatacopy(0, 0, calldatasize())
                    let success := delegatecall(gas(), _singleton, 0, calldatasize(), 0, 0)
                    returndatacopy(0, 0, returndatasize())
                    if eq(success, 0) {
                        revert(0, returndatasize())
                    }
                    return(0, returndatasize())
                }
            }
        }
        
        /// @title Proxy Factory - Allows to create new proxy contact and execute a message call to the new proxy within one transaction.
        /// @author Stefan George - <[email protected]>
        contract GnosisSafeProxyFactory {
            event ProxyCreation(GnosisSafeProxy proxy, address singleton);
        
            /// @dev Allows to create new proxy contact and execute a message call to the new proxy within one transaction.
            /// @param singleton Address of singleton contract.
            /// @param data Payload for message call sent to new proxy contract.
            function createProxy(address singleton, bytes memory data) public returns (GnosisSafeProxy proxy) {
                proxy = new GnosisSafeProxy(singleton);
                if (data.length > 0)
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        if eq(call(gas(), proxy, 0, add(data, 0x20), mload(data), 0, 0), 0) {
                            revert(0, 0)
                        }
                    }
                emit ProxyCreation(proxy, singleton);
            }
        
            /// @dev Allows to retrieve the runtime code of a deployed Proxy. This can be used to check that the expected Proxy was deployed.
            function proxyRuntimeCode() public pure returns (bytes memory) {
                return type(GnosisSafeProxy).runtimeCode;
            }
        
            /// @dev Allows to retrieve the creation code used for the Proxy deployment. With this it is easily possible to calculate predicted address.
            function proxyCreationCode() public pure returns (bytes memory) {
                return type(GnosisSafeProxy).creationCode;
            }
        
            /// @dev Allows to create new proxy contact using CREATE2 but it doesn't run the initializer.
            ///      This method is only meant as an utility to be called from other methods
            /// @param _singleton Address of singleton contract.
            /// @param initializer Payload for message call sent to new proxy contract.
            /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
            function deployProxyWithNonce(
                address _singleton,
                bytes memory initializer,
                uint256 saltNonce
            ) internal returns (GnosisSafeProxy proxy) {
                // If the initializer changes the proxy address should change too. Hashing the initializer data is cheaper than just concatinating it
                bytes32 salt = keccak256(abi.encodePacked(keccak256(initializer), saltNonce));
                bytes memory deploymentData = abi.encodePacked(type(GnosisSafeProxy).creationCode, uint256(uint160(_singleton)));
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    proxy := create2(0x0, add(0x20, deploymentData), mload(deploymentData), salt)
                }
                require(address(proxy) != address(0), "Create2 call failed");
            }
        
            /// @dev Allows to create new proxy contact and execute a message call to the new proxy within one transaction.
            /// @param _singleton Address of singleton contract.
            /// @param initializer Payload for message call sent to new proxy contract.
            /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
            function createProxyWithNonce(
                address _singleton,
                bytes memory initializer,
                uint256 saltNonce
            ) public returns (GnosisSafeProxy proxy) {
                proxy = deployProxyWithNonce(_singleton, initializer, saltNonce);
                if (initializer.length > 0)
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        if eq(call(gas(), proxy, 0, add(initializer, 0x20), mload(initializer), 0, 0), 0) {
                            revert(0, 0)
                        }
                    }
                emit ProxyCreation(proxy, _singleton);
            }
        
            /// @dev Allows to create new proxy contact, execute a message call to the new proxy and call a specified callback within one transaction
            /// @param _singleton Address of singleton contract.
            /// @param initializer Payload for message call sent to new proxy contract.
            /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
            /// @param callback Callback that will be invoced after the new proxy contract has been successfully deployed and initialized.
            function createProxyWithCallback(
                address _singleton,
                bytes memory initializer,
                uint256 saltNonce,
                IProxyCreationCallback callback
            ) public returns (GnosisSafeProxy proxy) {
                uint256 saltNonceWithCallback = uint256(keccak256(abi.encodePacked(saltNonce, callback)));
                proxy = createProxyWithNonce(_singleton, initializer, saltNonceWithCallback);
                if (address(callback) != address(0)) callback.proxyCreated(proxy, _singleton, initializer, saltNonce);
            }
        
            /// @dev Allows to get the address for a new proxy contact created via `createProxyWithNonce`
            ///      This method is only meant for address calculation purpose when you use an initializer that would revert,
            ///      therefore the response is returned with a revert. When calling this method set `from` to the address of the proxy factory.
            /// @param _singleton Address of singleton contract.
            /// @param initializer Payload for message call sent to new proxy contract.
            /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
            function calculateCreateProxyWithNonceAddress(
                address _singleton,
                bytes calldata initializer,
                uint256 saltNonce
            ) external returns (GnosisSafeProxy proxy) {
                proxy = deployProxyWithNonce(_singleton, initializer, saltNonce);
                revert(string(abi.encodePacked(proxy)));
            }
        }
        
        interface IProxyCreationCallback {
            function proxyCreated(
                GnosisSafeProxy proxy,
                address _singleton,
                bytes calldata initializer,
                uint256 saltNonce
            ) external;
        }

        File 3 of 4: NounsAuctionHouse
        // SPDX-License-Identifier: GPL-3.0
        /// @title The Nouns DAO auction house
        /*********************************
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░█████████░░█████████░░░ *
         * ░░░░░░██░░░████░░██░░░████░░░ *
         * ░░██████░░░████████░░░████░░░ *
         * ░░██░░██░░░████░░██░░░████░░░ *
         * ░░██░░██░░░████░░██░░░████░░░ *
         * ░░░░░░█████████░░█████████░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         *********************************/
        // LICENSE
        // NounsAuctionHouse.sol is a modified version of Zora's AuctionHouse.sol:
        // https://github.com/ourzora/auction-house/blob/54a12ec1a6cf562e49f0a4917990474b11350a2d/contracts/AuctionHouse.sol
        //
        // AuctionHouse.sol source code Copyright Zora licensed under the GPL-3.0 license.
        // With modifications by Nounders DAO.
        pragma solidity ^0.8.6;
        import { PausableUpgradeable } from '@openzeppelin/contracts-upgradeable/security/PausableUpgradeable.sol';
        import { ReentrancyGuardUpgradeable } from '@openzeppelin/contracts-upgradeable/security/ReentrancyGuardUpgradeable.sol';
        import { OwnableUpgradeable } from '@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol';
        import { IERC20 } from '@openzeppelin/contracts/token/ERC20/IERC20.sol';
        import { INounsAuctionHouse } from './interfaces/INounsAuctionHouse.sol';
        import { INounsToken } from './interfaces/INounsToken.sol';
        import { IWETH } from './interfaces/IWETH.sol';
        contract NounsAuctionHouse is INounsAuctionHouse, PausableUpgradeable, ReentrancyGuardUpgradeable, OwnableUpgradeable {
            // The Nouns ERC721 token contract
            INounsToken public nouns;
            // The address of the WETH contract
            address public weth;
            // The minimum amount of time left in an auction after a new bid is created
            uint256 public timeBuffer;
            // The minimum price accepted in an auction
            uint256 public reservePrice;
            // The minimum percentage difference between the last bid amount and the current bid
            uint8 public minBidIncrementPercentage;
            // The duration of a single auction
            uint256 public duration;
            // The active auction
            INounsAuctionHouse.Auction public auction;
            /**
             * @notice Initialize the auction house and base contracts,
             * populate configuration values, and pause the contract.
             * @dev This function can only be called once.
             */
            function initialize(
                INounsToken _nouns,
                address _weth,
                uint256 _timeBuffer,
                uint256 _reservePrice,
                uint8 _minBidIncrementPercentage,
                uint256 _duration
            ) external initializer {
                __Pausable_init();
                __ReentrancyGuard_init();
                __Ownable_init();
                _pause();
                nouns = _nouns;
                weth = _weth;
                timeBuffer = _timeBuffer;
                reservePrice = _reservePrice;
                minBidIncrementPercentage = _minBidIncrementPercentage;
                duration = _duration;
            }
            /**
             * @notice Settle the current auction, mint a new Noun, and put it up for auction.
             */
            function settleCurrentAndCreateNewAuction() external override nonReentrant whenNotPaused {
                _settleAuction();
                _createAuction();
            }
            /**
             * @notice Settle the current auction.
             * @dev This function can only be called when the contract is paused.
             */
            function settleAuction() external override whenPaused nonReentrant {
                _settleAuction();
            }
            /**
             * @notice Create a bid for a Noun, with a given amount.
             * @dev This contract only accepts payment in ETH.
             */
            function createBid(uint256 nounId) external payable override nonReentrant {
                INounsAuctionHouse.Auction memory _auction = auction;
                require(_auction.nounId == nounId, 'Noun not up for auction');
                require(block.timestamp < _auction.endTime, 'Auction expired');
                require(msg.value >= reservePrice, 'Must send at least reservePrice');
                require(
                    msg.value >= _auction.amount + ((_auction.amount * minBidIncrementPercentage) / 100),
                    'Must send more than last bid by minBidIncrementPercentage amount'
                );
                address payable lastBidder = _auction.bidder;
                // Refund the last bidder, if applicable
                if (lastBidder != address(0)) {
                    _safeTransferETHWithFallback(lastBidder, _auction.amount);
                }
                auction.amount = msg.value;
                auction.bidder = payable(msg.sender);
                // Extend the auction if the bid was received within `timeBuffer` of the auction end time
                bool extended = _auction.endTime - block.timestamp < timeBuffer;
                if (extended) {
                    auction.endTime = _auction.endTime = block.timestamp + timeBuffer;
                }
                emit AuctionBid(_auction.nounId, msg.sender, msg.value, extended);
                if (extended) {
                    emit AuctionExtended(_auction.nounId, _auction.endTime);
                }
            }
            /**
             * @notice Pause the Nouns auction house.
             * @dev This function can only be called by the owner when the
             * contract is unpaused. While no new auctions can be started when paused,
             * anyone can settle an ongoing auction.
             */
            function pause() external override onlyOwner {
                _pause();
            }
            /**
             * @notice Unpause the Nouns auction house.
             * @dev This function can only be called by the owner when the
             * contract is paused. If required, this function will start a new auction.
             */
            function unpause() external override onlyOwner {
                _unpause();
                if (auction.startTime == 0 || auction.settled) {
                    _createAuction();
                }
            }
            /**
             * @notice Set the auction time buffer.
             * @dev Only callable by the owner.
             */
            function setTimeBuffer(uint256 _timeBuffer) external override onlyOwner {
                timeBuffer = _timeBuffer;
                emit AuctionTimeBufferUpdated(_timeBuffer);
            }
            /**
             * @notice Set the auction reserve price.
             * @dev Only callable by the owner.
             */
            function setReservePrice(uint256 _reservePrice) external override onlyOwner {
                reservePrice = _reservePrice;
                emit AuctionReservePriceUpdated(_reservePrice);
            }
            /**
             * @notice Set the auction minimum bid increment percentage.
             * @dev Only callable by the owner.
             */
            function setMinBidIncrementPercentage(uint8 _minBidIncrementPercentage) external override onlyOwner {
                minBidIncrementPercentage = _minBidIncrementPercentage;
                emit AuctionMinBidIncrementPercentageUpdated(_minBidIncrementPercentage);
            }
            /**
             * @notice Create an auction.
             * @dev Store the auction details in the `auction` state variable and emit an AuctionCreated event.
             * If the mint reverts, the minter was updated without pausing this contract first. To remedy this,
             * catch the revert and pause this contract.
             */
            function _createAuction() internal {
                try nouns.mint() returns (uint256 nounId) {
                    uint256 startTime = block.timestamp;
                    uint256 endTime = startTime + duration;
                    auction = Auction({
                        nounId: nounId,
                        amount: 0,
                        startTime: startTime,
                        endTime: endTime,
                        bidder: payable(0),
                        settled: false
                    });
                    emit AuctionCreated(nounId, startTime, endTime);
                } catch Error(string memory) {
                    _pause();
                }
            }
            /**
             * @notice Settle an auction, finalizing the bid and paying out to the owner.
             * @dev If there are no bids, the Noun is burned.
             */
            function _settleAuction() internal {
                INounsAuctionHouse.Auction memory _auction = auction;
                require(_auction.startTime != 0, "Auction hasn't begun");
                require(!_auction.settled, 'Auction has already been settled');
                require(block.timestamp >= _auction.endTime, "Auction hasn't completed");
                auction.settled = true;
                if (_auction.bidder == address(0)) {
                    nouns.burn(_auction.nounId);
                } else {
                    nouns.transferFrom(address(this), _auction.bidder, _auction.nounId);
                }
                if (_auction.amount > 0) {
                    _safeTransferETHWithFallback(owner(), _auction.amount);
                }
                emit AuctionSettled(_auction.nounId, _auction.bidder, _auction.amount);
            }
            /**
             * @notice Transfer ETH. If the ETH transfer fails, wrap the ETH and try send it as WETH.
             */
            function _safeTransferETHWithFallback(address to, uint256 amount) internal {
                if (!_safeTransferETH(to, amount)) {
                    IWETH(weth).deposit{ value: amount }();
                    IERC20(weth).transfer(to, amount);
                }
            }
            /**
             * @notice Transfer ETH and return the success status.
             * @dev This function only forwards 30,000 gas to the callee.
             */
            function _safeTransferETH(address to, uint256 value) internal returns (bool) {
                (bool success, ) = to.call{ value: value, gas: 30_000 }(new bytes(0));
                return success;
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        import "../utils/ContextUpgradeable.sol";
        import "../proxy/utils/Initializable.sol";
        /**
         * @dev Contract module which allows children to implement an emergency stop
         * mechanism that can be triggered by an authorized account.
         *
         * This module is used through inheritance. It will make available the
         * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
         * the functions of your contract. Note that they will not be pausable by
         * simply including this module, only once the modifiers are put in place.
         */
        abstract contract PausableUpgradeable is Initializable, ContextUpgradeable {
            /**
             * @dev Emitted when the pause is triggered by `account`.
             */
            event Paused(address account);
            /**
             * @dev Emitted when the pause is lifted by `account`.
             */
            event Unpaused(address account);
            bool private _paused;
            /**
             * @dev Initializes the contract in unpaused state.
             */
            function __Pausable_init() internal initializer {
                __Context_init_unchained();
                __Pausable_init_unchained();
            }
            function __Pausable_init_unchained() internal initializer {
                _paused = false;
            }
            /**
             * @dev Returns true if the contract is paused, and false otherwise.
             */
            function paused() public view virtual returns (bool) {
                return _paused;
            }
            /**
             * @dev Modifier to make a function callable only when the contract is not paused.
             *
             * Requirements:
             *
             * - The contract must not be paused.
             */
            modifier whenNotPaused() {
                require(!paused(), "Pausable: paused");
                _;
            }
            /**
             * @dev Modifier to make a function callable only when the contract is paused.
             *
             * Requirements:
             *
             * - The contract must be paused.
             */
            modifier whenPaused() {
                require(paused(), "Pausable: not paused");
                _;
            }
            /**
             * @dev Triggers stopped state.
             *
             * Requirements:
             *
             * - The contract must not be paused.
             */
            function _pause() internal virtual whenNotPaused {
                _paused = true;
                emit Paused(_msgSender());
            }
            /**
             * @dev Returns to normal state.
             *
             * Requirements:
             *
             * - The contract must be paused.
             */
            function _unpause() internal virtual whenPaused {
                _paused = false;
                emit Unpaused(_msgSender());
            }
            uint256[49] private __gap;
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        import "../proxy/utils/Initializable.sol";
        /**
         * @dev Contract module that helps prevent reentrant calls to a function.
         *
         * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
         * available, which can be applied to functions to make sure there are no nested
         * (reentrant) calls to them.
         *
         * Note that because there is a single `nonReentrant` guard, functions marked as
         * `nonReentrant` may not call one another. This can be worked around by making
         * those functions `private`, and then adding `external` `nonReentrant` entry
         * points to them.
         *
         * TIP: If you would like to learn more about reentrancy and alternative ways
         * to protect against it, check out our blog post
         * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
         */
        abstract contract ReentrancyGuardUpgradeable is Initializable {
            // Booleans are more expensive than uint256 or any type that takes up a full
            // word because each write operation emits an extra SLOAD to first read the
            // slot's contents, replace the bits taken up by the boolean, and then write
            // back. This is the compiler's defense against contract upgrades and
            // pointer aliasing, and it cannot be disabled.
            // The values being non-zero value makes deployment a bit more expensive,
            // but in exchange the refund on every call to nonReentrant will be lower in
            // amount. Since refunds are capped to a percentage of the total
            // transaction's gas, it is best to keep them low in cases like this one, to
            // increase the likelihood of the full refund coming into effect.
            uint256 private constant _NOT_ENTERED = 1;
            uint256 private constant _ENTERED = 2;
            uint256 private _status;
            function __ReentrancyGuard_init() internal initializer {
                __ReentrancyGuard_init_unchained();
            }
            function __ReentrancyGuard_init_unchained() internal initializer {
                _status = _NOT_ENTERED;
            }
            /**
             * @dev Prevents a contract from calling itself, directly or indirectly.
             * Calling a `nonReentrant` function from another `nonReentrant`
             * function is not supported. It is possible to prevent this from happening
             * by making the `nonReentrant` function external, and make it call a
             * `private` function that does the actual work.
             */
            modifier nonReentrant() {
                // On the first call to nonReentrant, _notEntered will be true
                require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
                // Any calls to nonReentrant after this point will fail
                _status = _ENTERED;
                _;
                // By storing the original value once again, a refund is triggered (see
                // https://eips.ethereum.org/EIPS/eip-2200)
                _status = _NOT_ENTERED;
            }
            uint256[49] private __gap;
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        import "../utils/ContextUpgradeable.sol";
        import "../proxy/utils/Initializable.sol";
        /**
         * @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 OwnableUpgradeable is Initializable, ContextUpgradeable {
            address private _owner;
            event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
            /**
             * @dev Initializes the contract setting the deployer as the initial owner.
             */
            function __Ownable_init() internal initializer {
                __Context_init_unchained();
                __Ownable_init_unchained();
            }
            function __Ownable_init_unchained() internal initializer {
                _setOwner(_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 {
                _setOwner(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");
                _setOwner(newOwner);
            }
            function _setOwner(address newOwner) private {
                address oldOwner = _owner;
                _owner = newOwner;
                emit OwnershipTransferred(oldOwner, newOwner);
            }
            uint256[49] private __gap;
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        /**
         * @dev Interface of the ERC20 standard as defined in the EIP.
         */
        interface IERC20 {
            /**
             * @dev Returns the amount of tokens in existence.
             */
            function totalSupply() external view returns (uint256);
            /**
             * @dev Returns the amount of tokens owned by `account`.
             */
            function balanceOf(address account) external view returns (uint256);
            /**
             * @dev Moves `amount` tokens from the caller's account to `recipient`.
             *
             * Returns a boolean value indicating whether the operation succeeded.
             *
             * Emits a {Transfer} event.
             */
            function transfer(address recipient, uint256 amount) external returns (bool);
            /**
             * @dev Returns the remaining number of tokens that `spender` will be
             * allowed to spend on behalf of `owner` through {transferFrom}. This is
             * zero by default.
             *
             * This value changes when {approve} or {transferFrom} are called.
             */
            function allowance(address owner, address spender) external view returns (uint256);
            /**
             * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
             *
             * Returns a boolean value indicating whether the operation succeeded.
             *
             * IMPORTANT: Beware that changing an allowance with this method brings the risk
             * that someone may use both the old and the new allowance by unfortunate
             * transaction ordering. One possible solution to mitigate this race
             * condition is to first reduce the spender's allowance to 0 and set the
             * desired value afterwards:
             * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
             *
             * Emits an {Approval} event.
             */
            function approve(address spender, uint256 amount) external returns (bool);
            /**
             * @dev Moves `amount` tokens from `sender` to `recipient` using the
             * allowance mechanism. `amount` is then deducted from the caller's
             * allowance.
             *
             * Returns a boolean value indicating whether the operation succeeded.
             *
             * Emits a {Transfer} event.
             */
            function transferFrom(
                address sender,
                address recipient,
                uint256 amount
            ) external returns (bool);
            /**
             * @dev Emitted when `value` tokens are moved from one account (`from`) to
             * another (`to`).
             *
             * Note that `value` may be zero.
             */
            event Transfer(address indexed from, address indexed to, uint256 value);
            /**
             * @dev Emitted when the allowance of a `spender` for an `owner` is set by
             * a call to {approve}. `value` is the new allowance.
             */
            event Approval(address indexed owner, address indexed spender, uint256 value);
        }
        // SPDX-License-Identifier: GPL-3.0
        /// @title Interface for Noun Auction Houses
        /*********************************
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░█████████░░█████████░░░ *
         * ░░░░░░██░░░████░░██░░░████░░░ *
         * ░░██████░░░████████░░░████░░░ *
         * ░░██░░██░░░████░░██░░░████░░░ *
         * ░░██░░██░░░████░░██░░░████░░░ *
         * ░░░░░░█████████░░█████████░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         *********************************/
        pragma solidity ^0.8.6;
        interface INounsAuctionHouse {
            struct Auction {
                // ID for the Noun (ERC721 token ID)
                uint256 nounId;
                // The current highest bid amount
                uint256 amount;
                // The time that the auction started
                uint256 startTime;
                // The time that the auction is scheduled to end
                uint256 endTime;
                // The address of the current highest bid
                address payable bidder;
                // Whether or not the auction has been settled
                bool settled;
            }
            event AuctionCreated(uint256 indexed nounId, uint256 startTime, uint256 endTime);
            event AuctionBid(uint256 indexed nounId, address sender, uint256 value, bool extended);
            event AuctionExtended(uint256 indexed nounId, uint256 endTime);
            event AuctionSettled(uint256 indexed nounId, address winner, uint256 amount);
            event AuctionTimeBufferUpdated(uint256 timeBuffer);
            event AuctionReservePriceUpdated(uint256 reservePrice);
            event AuctionMinBidIncrementPercentageUpdated(uint256 minBidIncrementPercentage);
            function settleAuction() external;
            function settleCurrentAndCreateNewAuction() external;
            function createBid(uint256 nounId) external payable;
            function pause() external;
            function unpause() external;
            function setTimeBuffer(uint256 timeBuffer) external;
            function setReservePrice(uint256 reservePrice) external;
            function setMinBidIncrementPercentage(uint8 minBidIncrementPercentage) external;
        }
        // SPDX-License-Identifier: GPL-3.0
        /// @title Interface for NounsToken
        /*********************************
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░█████████░░█████████░░░ *
         * ░░░░░░██░░░████░░██░░░████░░░ *
         * ░░██████░░░████████░░░████░░░ *
         * ░░██░░██░░░████░░██░░░████░░░ *
         * ░░██░░██░░░████░░██░░░████░░░ *
         * ░░░░░░█████████░░█████████░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         *********************************/
        pragma solidity ^0.8.6;
        import { IERC721 } from '@openzeppelin/contracts/token/ERC721/IERC721.sol';
        import { INounsDescriptor } from './INounsDescriptor.sol';
        import { INounsSeeder } from './INounsSeeder.sol';
        interface INounsToken is IERC721 {
            event NounCreated(uint256 indexed tokenId, INounsSeeder.Seed seed);
            event NounBurned(uint256 indexed tokenId);
            event NoundersDAOUpdated(address noundersDAO);
            event MinterUpdated(address minter);
            event MinterLocked();
            event DescriptorUpdated(INounsDescriptor descriptor);
            event DescriptorLocked();
            event SeederUpdated(INounsSeeder seeder);
            event SeederLocked();
            function mint() external returns (uint256);
            function burn(uint256 tokenId) external;
            function dataURI(uint256 tokenId) external returns (string memory);
            function setNoundersDAO(address noundersDAO) external;
            function setMinter(address minter) external;
            function lockMinter() external;
            function setDescriptor(INounsDescriptor descriptor) external;
            function lockDescriptor() external;
            function setSeeder(INounsSeeder seeder) external;
            function lockSeeder() external;
        }
        // SPDX-License-Identifier: GPL-3.0
        pragma solidity ^0.8.6;
        interface IWETH {
            function deposit() external payable;
            function withdraw(uint256 wad) external;
            function transfer(address to, uint256 value) external returns (bool);
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        import "../proxy/utils/Initializable.sol";
        /*
         * @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 ContextUpgradeable is Initializable {
            function __Context_init() internal initializer {
                __Context_init_unchained();
            }
            function __Context_init_unchained() internal initializer {
            }
            function _msgSender() internal view virtual returns (address) {
                return msg.sender;
            }
            function _msgData() internal view virtual returns (bytes calldata) {
                return msg.data;
            }
            uint256[50] private __gap;
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        /**
         * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
         * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
         * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
         * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
         *
         * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
         * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
         *
         * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
         * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
         */
        abstract contract Initializable {
            /**
             * @dev Indicates that the contract has been initialized.
             */
            bool private _initialized;
            /**
             * @dev Indicates that the contract is in the process of being initialized.
             */
            bool private _initializing;
            /**
             * @dev Modifier to protect an initializer function from being invoked twice.
             */
            modifier initializer() {
                require(_initializing || !_initialized, "Initializable: contract is already initialized");
                bool isTopLevelCall = !_initializing;
                if (isTopLevelCall) {
                    _initializing = true;
                    _initialized = true;
                }
                _;
                if (isTopLevelCall) {
                    _initializing = false;
                }
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.0;
        import "../../utils/introspection/IERC165.sol";
        /**
         * @dev Required interface of an ERC721 compliant contract.
         */
        interface IERC721 is IERC165 {
            /**
             * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
             */
            event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
            /**
             * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
             */
            event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
            /**
             * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
             */
            event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
            /**
             * @dev Returns the number of tokens in ``owner``'s account.
             */
            function balanceOf(address owner) external view returns (uint256 balance);
            /**
             * @dev Returns the owner of the `tokenId` token.
             *
             * Requirements:
             *
             * - `tokenId` must exist.
             */
            function ownerOf(uint256 tokenId) external view returns (address owner);
            /**
             * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
             * are aware of the ERC721 protocol to prevent tokens from being forever locked.
             *
             * Requirements:
             *
             * - `from` cannot be the zero address.
             * - `to` cannot be the zero address.
             * - `tokenId` token must exist and be owned by `from`.
             * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
             * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
             *
             * Emits a {Transfer} event.
             */
            function safeTransferFrom(
                address from,
                address to,
                uint256 tokenId
            ) external;
            /**
             * @dev Transfers `tokenId` token from `from` to `to`.
             *
             * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
             *
             * Requirements:
             *
             * - `from` cannot be the zero address.
             * - `to` cannot be the zero address.
             * - `tokenId` token must be owned by `from`.
             * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
             *
             * Emits a {Transfer} event.
             */
            function transferFrom(
                address from,
                address to,
                uint256 tokenId
            ) external;
            /**
             * @dev Gives permission to `to` to transfer `tokenId` token to another account.
             * The approval is cleared when the token is transferred.
             *
             * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
             *
             * Requirements:
             *
             * - The caller must own the token or be an approved operator.
             * - `tokenId` must exist.
             *
             * Emits an {Approval} event.
             */
            function approve(address to, uint256 tokenId) external;
            /**
             * @dev Returns the account approved for `tokenId` token.
             *
             * Requirements:
             *
             * - `tokenId` must exist.
             */
            function getApproved(uint256 tokenId) external view returns (address operator);
            /**
             * @dev Approve or remove `operator` as an operator for the caller.
             * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
             *
             * Requirements:
             *
             * - The `operator` cannot be the caller.
             *
             * Emits an {ApprovalForAll} event.
             */
            function setApprovalForAll(address operator, bool _approved) external;
            /**
             * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
             *
             * See {setApprovalForAll}
             */
            function isApprovedForAll(address owner, address operator) external view returns (bool);
            /**
             * @dev Safely transfers `tokenId` token from `from` to `to`.
             *
             * Requirements:
             *
             * - `from` cannot be the zero address.
             * - `to` cannot be the zero address.
             * - `tokenId` token must exist and be owned by `from`.
             * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
             * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
             *
             * Emits a {Transfer} event.
             */
            function safeTransferFrom(
                address from,
                address to,
                uint256 tokenId,
                bytes calldata data
            ) external;
        }
        // SPDX-License-Identifier: GPL-3.0
        /// @title Interface for NounsDescriptor
        /*********************************
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░█████████░░█████████░░░ *
         * ░░░░░░██░░░████░░██░░░████░░░ *
         * ░░██████░░░████████░░░████░░░ *
         * ░░██░░██░░░████░░██░░░████░░░ *
         * ░░██░░██░░░████░░██░░░████░░░ *
         * ░░░░░░█████████░░█████████░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         *********************************/
        pragma solidity ^0.8.6;
        import { INounsSeeder } from './INounsSeeder.sol';
        interface INounsDescriptor {
            event PartsLocked();
            event DataURIToggled(bool enabled);
            event BaseURIUpdated(string baseURI);
            function arePartsLocked() external returns (bool);
            function isDataURIEnabled() external returns (bool);
            function baseURI() external returns (string memory);
            function palettes(uint8 paletteIndex, uint256 colorIndex) external view returns (string memory);
            function backgrounds(uint256 index) external view returns (string memory);
            function bodies(uint256 index) external view returns (bytes memory);
            function accessories(uint256 index) external view returns (bytes memory);
            function heads(uint256 index) external view returns (bytes memory);
            function glasses(uint256 index) external view returns (bytes memory);
            function backgroundCount() external view returns (uint256);
            function bodyCount() external view returns (uint256);
            function accessoryCount() external view returns (uint256);
            function headCount() external view returns (uint256);
            function glassesCount() external view returns (uint256);
            function addManyColorsToPalette(uint8 paletteIndex, string[] calldata newColors) external;
            function addManyBackgrounds(string[] calldata backgrounds) external;
            function addManyBodies(bytes[] calldata bodies) external;
            function addManyAccessories(bytes[] calldata accessories) external;
            function addManyHeads(bytes[] calldata heads) external;
            function addManyGlasses(bytes[] calldata glasses) external;
            function addColorToPalette(uint8 paletteIndex, string calldata color) external;
            function addBackground(string calldata background) external;
            function addBody(bytes calldata body) external;
            function addAccessory(bytes calldata accessory) external;
            function addHead(bytes calldata head) external;
            function addGlasses(bytes calldata glasses) external;
            function lockParts() external;
            function toggleDataURIEnabled() external;
            function setBaseURI(string calldata baseURI) external;
            function tokenURI(uint256 tokenId, INounsSeeder.Seed memory seed) external view returns (string memory);
            function dataURI(uint256 tokenId, INounsSeeder.Seed memory seed) external view returns (string memory);
            function genericDataURI(
                string calldata name,
                string calldata description,
                INounsSeeder.Seed memory seed
            ) external view returns (string memory);
            function generateSVGImage(INounsSeeder.Seed memory seed) external view returns (string memory);
        }
        // SPDX-License-Identifier: GPL-3.0
        /// @title Interface for NounsSeeder
        /*********************************
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░█████████░░█████████░░░ *
         * ░░░░░░██░░░████░░██░░░████░░░ *
         * ░░██████░░░████████░░░████░░░ *
         * ░░██░░██░░░████░░██░░░████░░░ *
         * ░░██░░██░░░████░░██░░░████░░░ *
         * ░░░░░░█████████░░█████████░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         * ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ *
         *********************************/
        pragma solidity ^0.8.6;
        import { INounsDescriptor } from './INounsDescriptor.sol';
        interface INounsSeeder {
            struct Seed {
                uint48 background;
                uint48 body;
                uint48 accessory;
                uint48 head;
                uint48 glasses;
            }
            function generateSeed(uint256 nounId, INounsDescriptor descriptor) external view returns (Seed memory);
        }
        // SPDX-License-Identifier: MIT
        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 4 of 4: GnosisSafe
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "./base/ModuleManager.sol";
        import "./base/OwnerManager.sol";
        import "./base/FallbackManager.sol";
        import "./base/GuardManager.sol";
        import "./common/EtherPaymentFallback.sol";
        import "./common/Singleton.sol";
        import "./common/SignatureDecoder.sol";
        import "./common/SecuredTokenTransfer.sol";
        import "./common/StorageAccessible.sol";
        import "./interfaces/ISignatureValidator.sol";
        import "./external/GnosisSafeMath.sol";
        /// @title Gnosis Safe - A multisignature wallet with support for confirmations using signed messages based on ERC191.
        /// @author Stefan George - <[email protected]>
        /// @author Richard Meissner - <[email protected]>
        contract GnosisSafe is
            EtherPaymentFallback,
            Singleton,
            ModuleManager,
            OwnerManager,
            SignatureDecoder,
            SecuredTokenTransfer,
            ISignatureValidatorConstants,
            FallbackManager,
            StorageAccessible,
            GuardManager
        {
            using GnosisSafeMath for uint256;
            string public constant VERSION = "1.3.0";
            // keccak256(
            //     "EIP712Domain(uint256 chainId,address verifyingContract)"
            // );
            bytes32 private constant DOMAIN_SEPARATOR_TYPEHASH = 0x47e79534a245952e8b16893a336b85a3d9ea9fa8c573f3d803afb92a79469218;
            // keccak256(
            //     "SafeTx(address to,uint256 value,bytes data,uint8 operation,uint256 safeTxGas,uint256 baseGas,uint256 gasPrice,address gasToken,address refundReceiver,uint256 nonce)"
            // );
            bytes32 private constant SAFE_TX_TYPEHASH = 0xbb8310d486368db6bd6f849402fdd73ad53d316b5a4b2644ad6efe0f941286d8;
            event SafeSetup(address indexed initiator, address[] owners, uint256 threshold, address initializer, address fallbackHandler);
            event ApproveHash(bytes32 indexed approvedHash, address indexed owner);
            event SignMsg(bytes32 indexed msgHash);
            event ExecutionFailure(bytes32 txHash, uint256 payment);
            event ExecutionSuccess(bytes32 txHash, uint256 payment);
            uint256 public nonce;
            bytes32 private _deprecatedDomainSeparator;
            // Mapping to keep track of all message hashes that have been approve by ALL REQUIRED owners
            mapping(bytes32 => uint256) public signedMessages;
            // Mapping to keep track of all hashes (message or transaction) that have been approve by ANY owners
            mapping(address => mapping(bytes32 => uint256)) public approvedHashes;
            // This constructor ensures that this contract can only be used as a master copy for Proxy contracts
            constructor() {
                // By setting the threshold it is not possible to call setup anymore,
                // so we create a Safe with 0 owners and threshold 1.
                // This is an unusable Safe, perfect for the singleton
                threshold = 1;
            }
            /// @dev Setup function sets initial storage of contract.
            /// @param _owners List of Safe owners.
            /// @param _threshold Number of required confirmations for a Safe transaction.
            /// @param to Contract address for optional delegate call.
            /// @param data Data payload for optional delegate call.
            /// @param fallbackHandler Handler for fallback calls to this contract
            /// @param paymentToken Token that should be used for the payment (0 is ETH)
            /// @param payment Value that should be paid
            /// @param paymentReceiver Adddress that should receive the payment (or 0 if tx.origin)
            function setup(
                address[] calldata _owners,
                uint256 _threshold,
                address to,
                bytes calldata data,
                address fallbackHandler,
                address paymentToken,
                uint256 payment,
                address payable paymentReceiver
            ) external {
                // setupOwners checks if the Threshold is already set, therefore preventing that this method is called twice
                setupOwners(_owners, _threshold);
                if (fallbackHandler != address(0)) internalSetFallbackHandler(fallbackHandler);
                // As setupOwners can only be called if the contract has not been initialized we don't need a check for setupModules
                setupModules(to, data);
                if (payment > 0) {
                    // To avoid running into issues with EIP-170 we reuse the handlePayment function (to avoid adjusting code of that has been verified we do not adjust the method itself)
                    // baseGas = 0, gasPrice = 1 and gas = payment => amount = (payment + 0) * 1 = payment
                    handlePayment(payment, 0, 1, paymentToken, paymentReceiver);
                }
                emit SafeSetup(msg.sender, _owners, _threshold, to, fallbackHandler);
            }
            /// @dev Allows to execute a Safe transaction confirmed by required number of owners and then pays the account that submitted the transaction.
            ///      Note: The fees are always transferred, even if the user transaction fails.
            /// @param to Destination address of Safe transaction.
            /// @param value Ether value of Safe transaction.
            /// @param data Data payload of Safe transaction.
            /// @param operation Operation type of Safe transaction.
            /// @param safeTxGas Gas that should be used for the Safe transaction.
            /// @param baseGas Gas costs that are independent of the transaction execution(e.g. base transaction fee, signature check, payment of the refund)
            /// @param gasPrice Gas price that should be used for the payment calculation.
            /// @param gasToken Token address (or 0 if ETH) that is used for the payment.
            /// @param refundReceiver Address of receiver of gas payment (or 0 if tx.origin).
            /// @param signatures Packed signature data ({bytes32 r}{bytes32 s}{uint8 v})
            function execTransaction(
                address to,
                uint256 value,
                bytes calldata data,
                Enum.Operation operation,
                uint256 safeTxGas,
                uint256 baseGas,
                uint256 gasPrice,
                address gasToken,
                address payable refundReceiver,
                bytes memory signatures
            ) public payable virtual returns (bool success) {
                bytes32 txHash;
                // Use scope here to limit variable lifetime and prevent `stack too deep` errors
                {
                    bytes memory txHashData =
                        encodeTransactionData(
                            // Transaction info
                            to,
                            value,
                            data,
                            operation,
                            safeTxGas,
                            // Payment info
                            baseGas,
                            gasPrice,
                            gasToken,
                            refundReceiver,
                            // Signature info
                            nonce
                        );
                    // Increase nonce and execute transaction.
                    nonce++;
                    txHash = keccak256(txHashData);
                    checkSignatures(txHash, txHashData, signatures);
                }
                address guard = getGuard();
                {
                    if (guard != address(0)) {
                        Guard(guard).checkTransaction(
                            // Transaction info
                            to,
                            value,
                            data,
                            operation,
                            safeTxGas,
                            // Payment info
                            baseGas,
                            gasPrice,
                            gasToken,
                            refundReceiver,
                            // Signature info
                            signatures,
                            msg.sender
                        );
                    }
                }
                // We require some gas to emit the events (at least 2500) after the execution and some to perform code until the execution (500)
                // We also include the 1/64 in the check that is not send along with a call to counteract potential shortings because of EIP-150
                require(gasleft() >= ((safeTxGas * 64) / 63).max(safeTxGas + 2500) + 500, "GS010");
                // Use scope here to limit variable lifetime and prevent `stack too deep` errors
                {
                    uint256 gasUsed = gasleft();
                    // If the gasPrice is 0 we assume that nearly all available gas can be used (it is always more than safeTxGas)
                    // We only substract 2500 (compared to the 3000 before) to ensure that the amount passed is still higher than safeTxGas
                    success = execute(to, value, data, operation, gasPrice == 0 ? (gasleft() - 2500) : safeTxGas);
                    gasUsed = gasUsed.sub(gasleft());
                    // If no safeTxGas and no gasPrice was set (e.g. both are 0), then the internal tx is required to be successful
                    // This makes it possible to use `estimateGas` without issues, as it searches for the minimum gas where the tx doesn't revert
                    require(success || safeTxGas != 0 || gasPrice != 0, "GS013");
                    // We transfer the calculated tx costs to the tx.origin to avoid sending it to intermediate contracts that have made calls
                    uint256 payment = 0;
                    if (gasPrice > 0) {
                        payment = handlePayment(gasUsed, baseGas, gasPrice, gasToken, refundReceiver);
                    }
                    if (success) emit ExecutionSuccess(txHash, payment);
                    else emit ExecutionFailure(txHash, payment);
                }
                {
                    if (guard != address(0)) {
                        Guard(guard).checkAfterExecution(txHash, success);
                    }
                }
            }
            function handlePayment(
                uint256 gasUsed,
                uint256 baseGas,
                uint256 gasPrice,
                address gasToken,
                address payable refundReceiver
            ) private returns (uint256 payment) {
                // solhint-disable-next-line avoid-tx-origin
                address payable receiver = refundReceiver == address(0) ? payable(tx.origin) : refundReceiver;
                if (gasToken == address(0)) {
                    // For ETH we will only adjust the gas price to not be higher than the actual used gas price
                    payment = gasUsed.add(baseGas).mul(gasPrice < tx.gasprice ? gasPrice : tx.gasprice);
                    require(receiver.send(payment), "GS011");
                } else {
                    payment = gasUsed.add(baseGas).mul(gasPrice);
                    require(transferToken(gasToken, receiver, payment), "GS012");
                }
            }
            /**
             * @dev Checks whether the signature provided is valid for the provided data, hash. Will revert otherwise.
             * @param dataHash Hash of the data (could be either a message hash or transaction hash)
             * @param data That should be signed (this is passed to an external validator contract)
             * @param signatures Signature data that should be verified. Can be ECDSA signature, contract signature (EIP-1271) or approved hash.
             */
            function checkSignatures(
                bytes32 dataHash,
                bytes memory data,
                bytes memory signatures
            ) public view {
                // Load threshold to avoid multiple storage loads
                uint256 _threshold = threshold;
                // Check that a threshold is set
                require(_threshold > 0, "GS001");
                checkNSignatures(dataHash, data, signatures, _threshold);
            }
            /**
             * @dev Checks whether the signature provided is valid for the provided data, hash. Will revert otherwise.
             * @param dataHash Hash of the data (could be either a message hash or transaction hash)
             * @param data That should be signed (this is passed to an external validator contract)
             * @param signatures Signature data that should be verified. Can be ECDSA signature, contract signature (EIP-1271) or approved hash.
             * @param requiredSignatures Amount of required valid signatures.
             */
            function checkNSignatures(
                bytes32 dataHash,
                bytes memory data,
                bytes memory signatures,
                uint256 requiredSignatures
            ) public view {
                // Check that the provided signature data is not too short
                require(signatures.length >= requiredSignatures.mul(65), "GS020");
                // There cannot be an owner with address 0.
                address lastOwner = address(0);
                address currentOwner;
                uint8 v;
                bytes32 r;
                bytes32 s;
                uint256 i;
                for (i = 0; i < requiredSignatures; i++) {
                    (v, r, s) = signatureSplit(signatures, i);
                    if (v == 0) {
                        // If v is 0 then it is a contract signature
                        // When handling contract signatures the address of the contract is encoded into r
                        currentOwner = address(uint160(uint256(r)));
                        // Check that signature data pointer (s) is not pointing inside the static part of the signatures bytes
                        // This check is not completely accurate, since it is possible that more signatures than the threshold are send.
                        // Here we only check that the pointer is not pointing inside the part that is being processed
                        require(uint256(s) >= requiredSignatures.mul(65), "GS021");
                        // Check that signature data pointer (s) is in bounds (points to the length of data -> 32 bytes)
                        require(uint256(s).add(32) <= signatures.length, "GS022");
                        // Check if the contract signature is in bounds: start of data is s + 32 and end is start + signature length
                        uint256 contractSignatureLen;
                        // solhint-disable-next-line no-inline-assembly
                        assembly {
                            contractSignatureLen := mload(add(add(signatures, s), 0x20))
                        }
                        require(uint256(s).add(32).add(contractSignatureLen) <= signatures.length, "GS023");
                        // Check signature
                        bytes memory contractSignature;
                        // solhint-disable-next-line no-inline-assembly
                        assembly {
                            // The signature data for contract signatures is appended to the concatenated signatures and the offset is stored in s
                            contractSignature := add(add(signatures, s), 0x20)
                        }
                        require(ISignatureValidator(currentOwner).isValidSignature(data, contractSignature) == EIP1271_MAGIC_VALUE, "GS024");
                    } else if (v == 1) {
                        // If v is 1 then it is an approved hash
                        // When handling approved hashes the address of the approver is encoded into r
                        currentOwner = address(uint160(uint256(r)));
                        // Hashes are automatically approved by the sender of the message or when they have been pre-approved via a separate transaction
                        require(msg.sender == currentOwner || approvedHashes[currentOwner][dataHash] != 0, "GS025");
                    } else if (v > 30) {
                        // If v > 30 then default va (27,28) has been adjusted for eth_sign flow
                        // To support eth_sign and similar we adjust v and hash the messageHash with the Ethereum message prefix before applying ecrecover
                        currentOwner = ecrecover(keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
        32", dataHash)), v - 4, r, s);
                    } else {
                        // Default is the ecrecover flow with the provided data hash
                        // Use ecrecover with the messageHash for EOA signatures
                        currentOwner = ecrecover(dataHash, v, r, s);
                    }
                    require(currentOwner > lastOwner && owners[currentOwner] != address(0) && currentOwner != SENTINEL_OWNERS, "GS026");
                    lastOwner = currentOwner;
                }
            }
            /// @dev Allows to estimate a Safe transaction.
            ///      This method is only meant for estimation purpose, therefore the call will always revert and encode the result in the revert data.
            ///      Since the `estimateGas` function includes refunds, call this method to get an estimated of the costs that are deducted from the safe with `execTransaction`
            /// @param to Destination address of Safe transaction.
            /// @param value Ether value of Safe transaction.
            /// @param data Data payload of Safe transaction.
            /// @param operation Operation type of Safe transaction.
            /// @return Estimate without refunds and overhead fees (base transaction and payload data gas costs).
            /// @notice Deprecated in favor of common/StorageAccessible.sol and will be removed in next version.
            function requiredTxGas(
                address to,
                uint256 value,
                bytes calldata data,
                Enum.Operation operation
            ) external returns (uint256) {
                uint256 startGas = gasleft();
                // We don't provide an error message here, as we use it to return the estimate
                require(execute(to, value, data, operation, gasleft()));
                uint256 requiredGas = startGas - gasleft();
                // Convert response to string and return via error message
                revert(string(abi.encodePacked(requiredGas)));
            }
            /**
             * @dev Marks a hash as approved. This can be used to validate a hash that is used by a signature.
             * @param hashToApprove The hash that should be marked as approved for signatures that are verified by this contract.
             */
            function approveHash(bytes32 hashToApprove) external {
                require(owners[msg.sender] != address(0), "GS030");
                approvedHashes[msg.sender][hashToApprove] = 1;
                emit ApproveHash(hashToApprove, msg.sender);
            }
            /// @dev Returns the chain id used by this contract.
            function getChainId() public view returns (uint256) {
                uint256 id;
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    id := chainid()
                }
                return id;
            }
            function domainSeparator() public view returns (bytes32) {
                return keccak256(abi.encode(DOMAIN_SEPARATOR_TYPEHASH, getChainId(), this));
            }
            /// @dev Returns the bytes that are hashed to be signed by owners.
            /// @param to Destination address.
            /// @param value Ether value.
            /// @param data Data payload.
            /// @param operation Operation type.
            /// @param safeTxGas Gas that should be used for the safe transaction.
            /// @param baseGas Gas costs for that are independent of the transaction execution(e.g. base transaction fee, signature check, payment of the refund)
            /// @param gasPrice Maximum gas price that should be used for this transaction.
            /// @param gasToken Token address (or 0 if ETH) that is used for the payment.
            /// @param refundReceiver Address of receiver of gas payment (or 0 if tx.origin).
            /// @param _nonce Transaction nonce.
            /// @return Transaction hash bytes.
            function encodeTransactionData(
                address to,
                uint256 value,
                bytes calldata data,
                Enum.Operation operation,
                uint256 safeTxGas,
                uint256 baseGas,
                uint256 gasPrice,
                address gasToken,
                address refundReceiver,
                uint256 _nonce
            ) public view returns (bytes memory) {
                bytes32 safeTxHash =
                    keccak256(
                        abi.encode(
                            SAFE_TX_TYPEHASH,
                            to,
                            value,
                            keccak256(data),
                            operation,
                            safeTxGas,
                            baseGas,
                            gasPrice,
                            gasToken,
                            refundReceiver,
                            _nonce
                        )
                    );
                return abi.encodePacked(bytes1(0x19), bytes1(0x01), domainSeparator(), safeTxHash);
            }
            /// @dev Returns hash to be signed by owners.
            /// @param to Destination address.
            /// @param value Ether value.
            /// @param data Data payload.
            /// @param operation Operation type.
            /// @param safeTxGas Fas that should be used for the safe transaction.
            /// @param baseGas Gas costs for data used to trigger the safe transaction.
            /// @param gasPrice Maximum gas price that should be used for this transaction.
            /// @param gasToken Token address (or 0 if ETH) that is used for the payment.
            /// @param refundReceiver Address of receiver of gas payment (or 0 if tx.origin).
            /// @param _nonce Transaction nonce.
            /// @return Transaction hash.
            function getTransactionHash(
                address to,
                uint256 value,
                bytes calldata data,
                Enum.Operation operation,
                uint256 safeTxGas,
                uint256 baseGas,
                uint256 gasPrice,
                address gasToken,
                address refundReceiver,
                uint256 _nonce
            ) public view returns (bytes32) {
                return keccak256(encodeTransactionData(to, value, data, operation, safeTxGas, baseGas, gasPrice, gasToken, refundReceiver, _nonce));
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "../common/Enum.sol";
        /// @title Executor - A contract that can execute transactions
        /// @author Richard Meissner - <[email protected]>
        contract Executor {
            function execute(
                address to,
                uint256 value,
                bytes memory data,
                Enum.Operation operation,
                uint256 txGas
            ) internal returns (bool success) {
                if (operation == Enum.Operation.DelegateCall) {
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        success := delegatecall(txGas, to, add(data, 0x20), mload(data), 0, 0)
                    }
                } else {
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        success := call(txGas, to, value, add(data, 0x20), mload(data), 0, 0)
                    }
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "../common/SelfAuthorized.sol";
        /// @title Fallback Manager - A contract that manages fallback calls made to this contract
        /// @author Richard Meissner - <[email protected]>
        contract FallbackManager is SelfAuthorized {
            event ChangedFallbackHandler(address handler);
            // keccak256("fallback_manager.handler.address")
            bytes32 internal constant FALLBACK_HANDLER_STORAGE_SLOT = 0x6c9a6c4a39284e37ed1cf53d337577d14212a4870fb976a4366c693b939918d5;
            function internalSetFallbackHandler(address handler) internal {
                bytes32 slot = FALLBACK_HANDLER_STORAGE_SLOT;
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    sstore(slot, handler)
                }
            }
            /// @dev Allows to add a contract to handle fallback calls.
            ///      Only fallback calls without value and with data will be forwarded.
            ///      This can only be done via a Safe transaction.
            /// @param handler contract to handle fallbacks calls.
            function setFallbackHandler(address handler) public authorized {
                internalSetFallbackHandler(handler);
                emit ChangedFallbackHandler(handler);
            }
            // solhint-disable-next-line payable-fallback,no-complex-fallback
            fallback() external {
                bytes32 slot = FALLBACK_HANDLER_STORAGE_SLOT;
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let handler := sload(slot)
                    if iszero(handler) {
                        return(0, 0)
                    }
                    calldatacopy(0, 0, calldatasize())
                    // The msg.sender address is shifted to the left by 12 bytes to remove the padding
                    // Then the address without padding is stored right after the calldata
                    mstore(calldatasize(), shl(96, caller()))
                    // Add 20 bytes for the address appended add the end
                    let success := call(gas(), handler, 0, 0, add(calldatasize(), 20), 0, 0)
                    returndatacopy(0, 0, returndatasize())
                    if iszero(success) {
                        revert(0, returndatasize())
                    }
                    return(0, returndatasize())
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "../common/Enum.sol";
        import "../common/SelfAuthorized.sol";
        interface Guard {
            function checkTransaction(
                address to,
                uint256 value,
                bytes memory data,
                Enum.Operation operation,
                uint256 safeTxGas,
                uint256 baseGas,
                uint256 gasPrice,
                address gasToken,
                address payable refundReceiver,
                bytes memory signatures,
                address msgSender
            ) external;
            function checkAfterExecution(bytes32 txHash, bool success) external;
        }
        /// @title Fallback Manager - A contract that manages fallback calls made to this contract
        /// @author Richard Meissner - <[email protected]>
        contract GuardManager is SelfAuthorized {
            event ChangedGuard(address guard);
            // keccak256("guard_manager.guard.address")
            bytes32 internal constant GUARD_STORAGE_SLOT = 0x4a204f620c8c5ccdca3fd54d003badd85ba500436a431f0cbda4f558c93c34c8;
            /// @dev Set a guard that checks transactions before execution
            /// @param guard The address of the guard to be used or the 0 address to disable the guard
            function setGuard(address guard) external authorized {
                bytes32 slot = GUARD_STORAGE_SLOT;
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    sstore(slot, guard)
                }
                emit ChangedGuard(guard);
            }
            function getGuard() internal view returns (address guard) {
                bytes32 slot = GUARD_STORAGE_SLOT;
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    guard := sload(slot)
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "../common/Enum.sol";
        import "../common/SelfAuthorized.sol";
        import "./Executor.sol";
        /// @title Module Manager - A contract that manages modules that can execute transactions via this contract
        /// @author Stefan George - <[email protected]>
        /// @author Richard Meissner - <[email protected]>
        contract ModuleManager is SelfAuthorized, Executor {
            event EnabledModule(address module);
            event DisabledModule(address module);
            event ExecutionFromModuleSuccess(address indexed module);
            event ExecutionFromModuleFailure(address indexed module);
            address internal constant SENTINEL_MODULES = address(0x1);
            mapping(address => address) internal modules;
            function setupModules(address to, bytes memory data) internal {
                require(modules[SENTINEL_MODULES] == address(0), "GS100");
                modules[SENTINEL_MODULES] = SENTINEL_MODULES;
                if (to != address(0))
                    // Setup has to complete successfully or transaction fails.
                    require(execute(to, 0, data, Enum.Operation.DelegateCall, gasleft()), "GS000");
            }
            /// @dev Allows to add a module to the whitelist.
            ///      This can only be done via a Safe transaction.
            /// @notice Enables the module `module` for the Safe.
            /// @param module Module to be whitelisted.
            function enableModule(address module) public authorized {
                // Module address cannot be null or sentinel.
                require(module != address(0) && module != SENTINEL_MODULES, "GS101");
                // Module cannot be added twice.
                require(modules[module] == address(0), "GS102");
                modules[module] = modules[SENTINEL_MODULES];
                modules[SENTINEL_MODULES] = module;
                emit EnabledModule(module);
            }
            /// @dev Allows to remove a module from the whitelist.
            ///      This can only be done via a Safe transaction.
            /// @notice Disables the module `module` for the Safe.
            /// @param prevModule Module that pointed to the module to be removed in the linked list
            /// @param module Module to be removed.
            function disableModule(address prevModule, address module) public authorized {
                // Validate module address and check that it corresponds to module index.
                require(module != address(0) && module != SENTINEL_MODULES, "GS101");
                require(modules[prevModule] == module, "GS103");
                modules[prevModule] = modules[module];
                modules[module] = address(0);
                emit DisabledModule(module);
            }
            /// @dev Allows a Module to execute a Safe transaction without any further confirmations.
            /// @param to Destination address of module transaction.
            /// @param value Ether value of module transaction.
            /// @param data Data payload of module transaction.
            /// @param operation Operation type of module transaction.
            function execTransactionFromModule(
                address to,
                uint256 value,
                bytes memory data,
                Enum.Operation operation
            ) public virtual returns (bool success) {
                // Only whitelisted modules are allowed.
                require(msg.sender != SENTINEL_MODULES && modules[msg.sender] != address(0), "GS104");
                // Execute transaction without further confirmations.
                success = execute(to, value, data, operation, gasleft());
                if (success) emit ExecutionFromModuleSuccess(msg.sender);
                else emit ExecutionFromModuleFailure(msg.sender);
            }
            /// @dev Allows a Module to execute a Safe transaction without any further confirmations and return data
            /// @param to Destination address of module transaction.
            /// @param value Ether value of module transaction.
            /// @param data Data payload of module transaction.
            /// @param operation Operation type of module transaction.
            function execTransactionFromModuleReturnData(
                address to,
                uint256 value,
                bytes memory data,
                Enum.Operation operation
            ) public returns (bool success, bytes memory returnData) {
                success = execTransactionFromModule(to, value, data, operation);
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    // Load free memory location
                    let ptr := mload(0x40)
                    // We allocate memory for the return data by setting the free memory location to
                    // current free memory location + data size + 32 bytes for data size value
                    mstore(0x40, add(ptr, add(returndatasize(), 0x20)))
                    // Store the size
                    mstore(ptr, returndatasize())
                    // Store the data
                    returndatacopy(add(ptr, 0x20), 0, returndatasize())
                    // Point the return data to the correct memory location
                    returnData := ptr
                }
            }
            /// @dev Returns if an module is enabled
            /// @return True if the module is enabled
            function isModuleEnabled(address module) public view returns (bool) {
                return SENTINEL_MODULES != module && modules[module] != address(0);
            }
            /// @dev Returns array of modules.
            /// @param start Start of the page.
            /// @param pageSize Maximum number of modules that should be returned.
            /// @return array Array of modules.
            /// @return next Start of the next page.
            function getModulesPaginated(address start, uint256 pageSize) external view returns (address[] memory array, address next) {
                // Init array with max page size
                array = new address[](pageSize);
                // Populate return array
                uint256 moduleCount = 0;
                address currentModule = modules[start];
                while (currentModule != address(0x0) && currentModule != SENTINEL_MODULES && moduleCount < pageSize) {
                    array[moduleCount] = currentModule;
                    currentModule = modules[currentModule];
                    moduleCount++;
                }
                next = currentModule;
                // Set correct size of returned array
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    mstore(array, moduleCount)
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "../common/SelfAuthorized.sol";
        /// @title OwnerManager - Manages a set of owners and a threshold to perform actions.
        /// @author Stefan George - <[email protected]>
        /// @author Richard Meissner - <[email protected]>
        contract OwnerManager is SelfAuthorized {
            event AddedOwner(address owner);
            event RemovedOwner(address owner);
            event ChangedThreshold(uint256 threshold);
            address internal constant SENTINEL_OWNERS = address(0x1);
            mapping(address => address) internal owners;
            uint256 internal ownerCount;
            uint256 internal threshold;
            /// @dev Setup function sets initial storage of contract.
            /// @param _owners List of Safe owners.
            /// @param _threshold Number of required confirmations for a Safe transaction.
            function setupOwners(address[] memory _owners, uint256 _threshold) internal {
                // Threshold can only be 0 at initialization.
                // Check ensures that setup function can only be called once.
                require(threshold == 0, "GS200");
                // Validate that threshold is smaller than number of added owners.
                require(_threshold <= _owners.length, "GS201");
                // There has to be at least one Safe owner.
                require(_threshold >= 1, "GS202");
                // Initializing Safe owners.
                address currentOwner = SENTINEL_OWNERS;
                for (uint256 i = 0; i < _owners.length; i++) {
                    // Owner address cannot be null.
                    address owner = _owners[i];
                    require(owner != address(0) && owner != SENTINEL_OWNERS && owner != address(this) && currentOwner != owner, "GS203");
                    // No duplicate owners allowed.
                    require(owners[owner] == address(0), "GS204");
                    owners[currentOwner] = owner;
                    currentOwner = owner;
                }
                owners[currentOwner] = SENTINEL_OWNERS;
                ownerCount = _owners.length;
                threshold = _threshold;
            }
            /// @dev Allows to add a new owner to the Safe and update the threshold at the same time.
            ///      This can only be done via a Safe transaction.
            /// @notice Adds the owner `owner` to the Safe and updates the threshold to `_threshold`.
            /// @param owner New owner address.
            /// @param _threshold New threshold.
            function addOwnerWithThreshold(address owner, uint256 _threshold) public authorized {
                // Owner address cannot be null, the sentinel or the Safe itself.
                require(owner != address(0) && owner != SENTINEL_OWNERS && owner != address(this), "GS203");
                // No duplicate owners allowed.
                require(owners[owner] == address(0), "GS204");
                owners[owner] = owners[SENTINEL_OWNERS];
                owners[SENTINEL_OWNERS] = owner;
                ownerCount++;
                emit AddedOwner(owner);
                // Change threshold if threshold was changed.
                if (threshold != _threshold) changeThreshold(_threshold);
            }
            /// @dev Allows to remove an owner from the Safe and update the threshold at the same time.
            ///      This can only be done via a Safe transaction.
            /// @notice Removes the owner `owner` from the Safe and updates the threshold to `_threshold`.
            /// @param prevOwner Owner that pointed to the owner to be removed in the linked list
            /// @param owner Owner address to be removed.
            /// @param _threshold New threshold.
            function removeOwner(
                address prevOwner,
                address owner,
                uint256 _threshold
            ) public authorized {
                // Only allow to remove an owner, if threshold can still be reached.
                require(ownerCount - 1 >= _threshold, "GS201");
                // Validate owner address and check that it corresponds to owner index.
                require(owner != address(0) && owner != SENTINEL_OWNERS, "GS203");
                require(owners[prevOwner] == owner, "GS205");
                owners[prevOwner] = owners[owner];
                owners[owner] = address(0);
                ownerCount--;
                emit RemovedOwner(owner);
                // Change threshold if threshold was changed.
                if (threshold != _threshold) changeThreshold(_threshold);
            }
            /// @dev Allows to swap/replace an owner from the Safe with another address.
            ///      This can only be done via a Safe transaction.
            /// @notice Replaces the owner `oldOwner` in the Safe with `newOwner`.
            /// @param prevOwner Owner that pointed to the owner to be replaced in the linked list
            /// @param oldOwner Owner address to be replaced.
            /// @param newOwner New owner address.
            function swapOwner(
                address prevOwner,
                address oldOwner,
                address newOwner
            ) public authorized {
                // Owner address cannot be null, the sentinel or the Safe itself.
                require(newOwner != address(0) && newOwner != SENTINEL_OWNERS && newOwner != address(this), "GS203");
                // No duplicate owners allowed.
                require(owners[newOwner] == address(0), "GS204");
                // Validate oldOwner address and check that it corresponds to owner index.
                require(oldOwner != address(0) && oldOwner != SENTINEL_OWNERS, "GS203");
                require(owners[prevOwner] == oldOwner, "GS205");
                owners[newOwner] = owners[oldOwner];
                owners[prevOwner] = newOwner;
                owners[oldOwner] = address(0);
                emit RemovedOwner(oldOwner);
                emit AddedOwner(newOwner);
            }
            /// @dev Allows to update the number of required confirmations by Safe owners.
            ///      This can only be done via a Safe transaction.
            /// @notice Changes the threshold of the Safe to `_threshold`.
            /// @param _threshold New threshold.
            function changeThreshold(uint256 _threshold) public authorized {
                // Validate that threshold is smaller than number of owners.
                require(_threshold <= ownerCount, "GS201");
                // There has to be at least one Safe owner.
                require(_threshold >= 1, "GS202");
                threshold = _threshold;
                emit ChangedThreshold(threshold);
            }
            function getThreshold() public view returns (uint256) {
                return threshold;
            }
            function isOwner(address owner) public view returns (bool) {
                return owner != SENTINEL_OWNERS && owners[owner] != address(0);
            }
            /// @dev Returns array of owners.
            /// @return Array of Safe owners.
            function getOwners() public view returns (address[] memory) {
                address[] memory array = new address[](ownerCount);
                // populate return array
                uint256 index = 0;
                address currentOwner = owners[SENTINEL_OWNERS];
                while (currentOwner != SENTINEL_OWNERS) {
                    array[index] = currentOwner;
                    currentOwner = owners[currentOwner];
                    index++;
                }
                return array;
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title Enum - Collection of enums
        /// @author Richard Meissner - <[email protected]>
        contract Enum {
            enum Operation {Call, DelegateCall}
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title EtherPaymentFallback - A contract that has a fallback to accept ether payments
        /// @author Richard Meissner - <[email protected]>
        contract EtherPaymentFallback {
            event SafeReceived(address indexed sender, uint256 value);
            /// @dev Fallback function accepts Ether transactions.
            receive() external payable {
                emit SafeReceived(msg.sender, msg.value);
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title SecuredTokenTransfer - Secure token transfer
        /// @author Richard Meissner - <[email protected]>
        contract SecuredTokenTransfer {
            /// @dev Transfers a token and returns if it was a success
            /// @param token Token that should be transferred
            /// @param receiver Receiver to whom the token should be transferred
            /// @param amount The amount of tokens that should be transferred
            function transferToken(
                address token,
                address receiver,
                uint256 amount
            ) internal returns (bool transferred) {
                // 0xa9059cbb - keccack("transfer(address,uint256)")
                bytes memory data = abi.encodeWithSelector(0xa9059cbb, receiver, amount);
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    // We write the return value to scratch space.
                    // See https://docs.soliditylang.org/en/v0.7.6/internals/layout_in_memory.html#layout-in-memory
                    let success := call(sub(gas(), 10000), token, 0, add(data, 0x20), mload(data), 0, 0x20)
                    switch returndatasize()
                        case 0 {
                            transferred := success
                        }
                        case 0x20 {
                            transferred := iszero(or(iszero(success), iszero(mload(0))))
                        }
                        default {
                            transferred := 0
                        }
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title SelfAuthorized - authorizes current contract to perform actions
        /// @author Richard Meissner - <[email protected]>
        contract SelfAuthorized {
            function requireSelfCall() private view {
                require(msg.sender == address(this), "GS031");
            }
            modifier authorized() {
                // This is a function call as it minimized the bytecode size
                requireSelfCall();
                _;
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title SignatureDecoder - Decodes signatures that a encoded as bytes
        /// @author Richard Meissner - <[email protected]>
        contract SignatureDecoder {
            /// @dev divides bytes signature into `uint8 v, bytes32 r, bytes32 s`.
            /// @notice Make sure to peform a bounds check for @param pos, to avoid out of bounds access on @param signatures
            /// @param pos which signature to read. A prior bounds check of this parameter should be performed, to avoid out of bounds access
            /// @param signatures concatenated rsv signatures
            function signatureSplit(bytes memory signatures, uint256 pos)
                internal
                pure
                returns (
                    uint8 v,
                    bytes32 r,
                    bytes32 s
                )
            {
                // The signature format is a compact form of:
                //   {bytes32 r}{bytes32 s}{uint8 v}
                // Compact means, uint8 is not padded to 32 bytes.
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let signaturePos := mul(0x41, pos)
                    r := mload(add(signatures, add(signaturePos, 0x20)))
                    s := mload(add(signatures, add(signaturePos, 0x40)))
                    // Here we are loading the last 32 bytes, including 31 bytes
                    // of 's'. There is no 'mload8' to do this.
                    //
                    // 'byte' is not working due to the Solidity parser, so lets
                    // use the second best option, 'and'
                    v := and(mload(add(signatures, add(signaturePos, 0x41))), 0xff)
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title Singleton - Base for singleton contracts (should always be first super contract)
        ///         This contract is tightly coupled to our proxy contract (see `proxies/GnosisSafeProxy.sol`)
        /// @author Richard Meissner - <[email protected]>
        contract Singleton {
            // singleton always needs to be first declared variable, to ensure that it is at the same location as in the Proxy contract.
            // It should also always be ensured that the address is stored alone (uses a full word)
            address private singleton;
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title StorageAccessible - generic base contract that allows callers to access all internal storage.
        /// @notice See https://github.com/gnosis/util-contracts/blob/bb5fe5fb5df6d8400998094fb1b32a178a47c3a1/contracts/StorageAccessible.sol
        contract StorageAccessible {
            /**
             * @dev Reads `length` bytes of storage in the currents contract
             * @param offset - the offset in the current contract's storage in words to start reading from
             * @param length - the number of words (32 bytes) of data to read
             * @return the bytes that were read.
             */
            function getStorageAt(uint256 offset, uint256 length) public view returns (bytes memory) {
                bytes memory result = new bytes(length * 32);
                for (uint256 index = 0; index < length; index++) {
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        let word := sload(add(offset, index))
                        mstore(add(add(result, 0x20), mul(index, 0x20)), word)
                    }
                }
                return result;
            }
            /**
             * @dev Performs a delegetecall on a targetContract in the context of self.
             * Internally reverts execution to avoid side effects (making it static).
             *
             * This method reverts with data equal to `abi.encode(bool(success), bytes(response))`.
             * Specifically, the `returndata` after a call to this method will be:
             * `success:bool || response.length:uint256 || response:bytes`.
             *
             * @param targetContract Address of the contract containing the code to execute.
             * @param calldataPayload Calldata that should be sent to the target contract (encoded method name and arguments).
             */
            function simulateAndRevert(address targetContract, bytes memory calldataPayload) external {
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let success := delegatecall(gas(), targetContract, add(calldataPayload, 0x20), mload(calldataPayload), 0, 0)
                    mstore(0x00, success)
                    mstore(0x20, returndatasize())
                    returndatacopy(0x40, 0, returndatasize())
                    revert(0, add(returndatasize(), 0x40))
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /**
         * @title GnosisSafeMath
         * @dev Math operations with safety checks that revert on error
         * Renamed from SafeMath to GnosisSafeMath to avoid conflicts
         * TODO: remove once open zeppelin update to solc 0.5.0
         */
        library GnosisSafeMath {
            /**
             * @dev Multiplies two numbers, reverts on overflow.
             */
            function mul(uint256 a, uint256 b) internal pure returns (uint256) {
                // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
                // benefit is lost if 'b' is also tested.
                // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
                if (a == 0) {
                    return 0;
                }
                uint256 c = a * b;
                require(c / a == b);
                return c;
            }
            /**
             * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
             */
            function sub(uint256 a, uint256 b) internal pure returns (uint256) {
                require(b <= a);
                uint256 c = a - b;
                return c;
            }
            /**
             * @dev Adds two numbers, reverts on overflow.
             */
            function add(uint256 a, uint256 b) internal pure returns (uint256) {
                uint256 c = a + b;
                require(c >= a);
                return c;
            }
            /**
             * @dev Returns the largest of two numbers.
             */
            function max(uint256 a, uint256 b) internal pure returns (uint256) {
                return a >= b ? a : b;
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        contract ISignatureValidatorConstants {
            // bytes4(keccak256("isValidSignature(bytes,bytes)")
            bytes4 internal constant EIP1271_MAGIC_VALUE = 0x20c13b0b;
        }
        abstract contract ISignatureValidator is ISignatureValidatorConstants {
            /**
             * @dev Should return whether the signature provided is valid for the provided data
             * @param _data Arbitrary length data signed on the behalf of address(this)
             * @param _signature Signature byte array associated with _data
             *
             * MUST return the bytes4 magic value 0x20c13b0b when function passes.
             * MUST NOT modify state (using STATICCALL for solc < 0.5, view modifier for solc > 0.5)
             * MUST allow external calls
             */
            function isValidSignature(bytes memory _data, bytes memory _signature) public view virtual returns (bytes4);
        }