ETH Price: $2,532.86 (-1.22%)
Gas: 0.32 Gwei

Transaction Decoder

Block:
17007825 at Apr-09-2023 02:32:35 AM +UTC
Transaction Fee:
0.002680455976052913 ETH $6.79
Gas Used:
155,601 Gas / 17.226470113 Gwei

Emitted Events:

173 ERC1967Proxy.0xe2a04703133f69c931bb48449c0d5170df8c68b48c951e992fa01bbd7086c6d3( 0xe2a04703133f69c931bb48449c0d5170df8c68b48c951e992fa01bbd7086c6d3, 0000000000000000000000000000000000000000000000000000000000001854, 0000000000000000000000000000000000000000000000000000000000000723 )

Account State Difference:

  Address   Before After State Difference Code
0x25902307...9c4D77820
(Lido: Execution Layer Rewards Vault)
109.400374281526206291 Eth109.400389841626206291 Eth0.0000155601
0x3fe858e9...518375306 2.92760729194435433 Eth2.92964329194435433 Eth0.002036
0xc0312Ba4...99b4A73a1
0.014953756041564204 Eth
Nonce: 137
0.009637300065511291 Eth
Nonce: 138
0.005316455976052913
0xeB81D250...Da71C3579 0.005293478241590981 Eth0.005893478241590981 Eth0.0006

Execution Trace

ETH 0.002636 ERC1967Proxy.b1caef21( )
  • ETH 0.002636 0x95d6840785a51e7e9d7fd3b33894c5908c695de5.b1caef21( )
    • Null: 0x000...001.5fd81aab( )
    • Token.ownerOf( tokenId=1827 ) => ( 0xc0312Ba4346099D53799Ed39aF5CA9F99b4A73a1 )
    • Token.ownerOf( tokenId=1914 ) => ( 0xeB81D250125cf30F755A6A84162eF1aDa71C3579 )
    • Token.ownerOf( tokenId=1914 ) => ( 0xeB81D250125cf30F755A6A84162eF1aDa71C3579 )
    • ETH 0.002036 0x3fe858e91af32bbf23c01fd43b15082518375306.CALL( )
    • ETH 0.0006 0xeb81d250125cf30f755a6a84162ef1ada71c3579.CALL( )
      File 1 of 2: ERC1967Proxy
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.8.0;
      import "@openzeppelin/contracts/proxy/beacon/BeaconProxy.sol";
      import "@openzeppelin/contracts/proxy/beacon/UpgradeableBeacon.sol";
      import "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";
      import "@openzeppelin/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
      import "@openzeppelin/contracts/proxy/transparent/ProxyAdmin.sol";
      // Kept for backwards compatibility with older versions of Hardhat and Truffle plugins.
      contract AdminUpgradeabilityProxy is TransparentUpgradeableProxy {
          constructor(address logic, address admin, bytes memory data) payable TransparentUpgradeableProxy(logic, admin, data) {}
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.8.0;
      import "./IBeacon.sol";
      import "../Proxy.sol";
      import "../ERC1967/ERC1967Upgrade.sol";
      /**
       * @dev This contract implements a proxy that gets the implementation address for each call from a {UpgradeableBeacon}.
       *
       * The beacon address is stored in storage slot `uint256(keccak256('eip1967.proxy.beacon')) - 1`, so that it doesn't
       * conflict with the storage layout of the implementation behind the proxy.
       *
       * _Available since v3.4._
       */
      contract BeaconProxy is Proxy, ERC1967Upgrade {
          /**
           * @dev Initializes the proxy with `beacon`.
           *
           * If `data` is nonempty, it's used as data in a delegate call to the implementation returned by the beacon. This
           * will typically be an encoded function call, and allows initializating the storage of the proxy like a Solidity
           * constructor.
           *
           * Requirements:
           *
           * - `beacon` must be a contract with the interface {IBeacon}.
           */
          constructor(address beacon, bytes memory data) payable {
              assert(_BEACON_SLOT == bytes32(uint256(keccak256("eip1967.proxy.beacon")) - 1));
              _upgradeBeaconToAndCall(beacon, data, false);
          }
          /**
           * @dev Returns the current beacon address.
           */
          function _beacon() internal view virtual returns (address) {
              return _getBeacon();
          }
          /**
           * @dev Returns the current implementation address of the associated beacon.
           */
          function _implementation() internal view virtual override returns (address) {
              return IBeacon(_getBeacon()).implementation();
          }
          /**
           * @dev Changes the proxy to use a new beacon. Deprecated: see {_upgradeBeaconToAndCall}.
           *
           * If `data` is nonempty, it's used as data in a delegate call to the implementation returned by the beacon.
           *
           * Requirements:
           *
           * - `beacon` must be a contract.
           * - The implementation returned by `beacon` must be a contract.
           */
          function _setBeacon(address beacon, bytes memory data) internal virtual {
              _upgradeBeaconToAndCall(beacon, data, false);
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.8.0;
      import "./IBeacon.sol";
      import "../../access/Ownable.sol";
      import "../../utils/Address.sol";
      /**
       * @dev This contract is used in conjunction with one or more instances of {BeaconProxy} to determine their
       * implementation contract, which is where they will delegate all function calls.
       *
       * An owner is able to change the implementation the beacon points to, thus upgrading the proxies that use this beacon.
       */
      contract UpgradeableBeacon is IBeacon, Ownable {
          address private _implementation;
          /**
           * @dev Emitted when the implementation returned by the beacon is changed.
           */
          event Upgraded(address indexed implementation);
          /**
           * @dev Sets the address of the initial implementation, and the deployer account as the owner who can upgrade the
           * beacon.
           */
          constructor(address implementation_) {
              _setImplementation(implementation_);
          }
          /**
           * @dev Returns the current implementation address.
           */
          function implementation() public view virtual override returns (address) {
              return _implementation;
          }
          /**
           * @dev Upgrades the beacon to a new implementation.
           *
           * Emits an {Upgraded} event.
           *
           * Requirements:
           *
           * - msg.sender must be the owner of the contract.
           * - `newImplementation` must be a contract.
           */
          function upgradeTo(address newImplementation) public virtual onlyOwner {
              _setImplementation(newImplementation);
              emit Upgraded(newImplementation);
          }
          /**
           * @dev Sets the implementation contract address for this beacon
           *
           * Requirements:
           *
           * - `newImplementation` must be a contract.
           */
          function _setImplementation(address newImplementation) private {
              require(Address.isContract(newImplementation), "UpgradeableBeacon: implementation is not a contract");
              _implementation = newImplementation;
          }
      }
      // 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;
      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 "./TransparentUpgradeableProxy.sol";
      import "../../access/Ownable.sol";
      /**
       * @dev This is an auxiliary contract meant to be assigned as the admin of a {TransparentUpgradeableProxy}. For an
       * explanation of why you would want to use this see the documentation for {TransparentUpgradeableProxy}.
       */
      contract ProxyAdmin is Ownable {
          /**
           * @dev Returns the current implementation of `proxy`.
           *
           * Requirements:
           *
           * - This contract must be the admin of `proxy`.
           */
          function getProxyImplementation(TransparentUpgradeableProxy proxy) public view virtual returns (address) {
              // We need to manually run the static call since the getter cannot be flagged as view
              // bytes4(keccak256("implementation()")) == 0x5c60da1b
              (bool success, bytes memory returndata) = address(proxy).staticcall(hex"5c60da1b");
              require(success);
              return abi.decode(returndata, (address));
          }
          /**
           * @dev Returns the current admin of `proxy`.
           *
           * Requirements:
           *
           * - This contract must be the admin of `proxy`.
           */
          function getProxyAdmin(TransparentUpgradeableProxy proxy) public view virtual returns (address) {
              // We need to manually run the static call since the getter cannot be flagged as view
              // bytes4(keccak256("admin()")) == 0xf851a440
              (bool success, bytes memory returndata) = address(proxy).staticcall(hex"f851a440");
              require(success);
              return abi.decode(returndata, (address));
          }
          /**
           * @dev Changes the admin of `proxy` to `newAdmin`.
           *
           * Requirements:
           *
           * - This contract must be the current admin of `proxy`.
           */
          function changeProxyAdmin(TransparentUpgradeableProxy proxy, address newAdmin) public virtual onlyOwner {
              proxy.changeAdmin(newAdmin);
          }
          /**
           * @dev Upgrades `proxy` to `implementation`. See {TransparentUpgradeableProxy-upgradeTo}.
           *
           * Requirements:
           *
           * - This contract must be the admin of `proxy`.
           */
          function upgrade(TransparentUpgradeableProxy proxy, address implementation) public virtual onlyOwner {
              proxy.upgradeTo(implementation);
          }
          /**
           * @dev Upgrades `proxy` to `implementation` and calls a function on the new implementation. See
           * {TransparentUpgradeableProxy-upgradeToAndCall}.
           *
           * Requirements:
           *
           * - This contract must be the admin of `proxy`.
           */
          function upgradeAndCall(TransparentUpgradeableProxy proxy, address implementation, bytes memory data) public payable virtual onlyOwner {
              proxy.upgradeToAndCall{value: msg.value}(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 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 {
              // solhint-disable-next-line no-inline-assembly
              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 {
              _setImplementation(newImplementation);
              emit Upgraded(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
                  _setImplementation(newImplementation);
                  emit Upgraded(newImplementation);
              }
          }
          /**
           * @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);
              }
          }
          /**
           * @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;
          }
      }
      // 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;
              // solhint-disable-next-line no-inline-assembly
              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");
              // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
              (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");
              // solhint-disable-next-line avoid-low-level-calls
              (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");
              // solhint-disable-next-line avoid-low-level-calls
              (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");
              // solhint-disable-next-line avoid-low-level-calls
              (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
                      // solhint-disable-next-line no-inline-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
              }
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.8.0;
      import "../utils/Context.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 Ownable is Context {
          address private _owner;
          event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
          /**
           * @dev Initializes the contract setting the deployer as the initial owner.
           */
          constructor () {
              address msgSender = _msgSender();
              _owner = msgSender;
              emit OwnershipTransferred(address(0), 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 {
              emit OwnershipTransferred(_owner, address(0));
              _owner = 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");
              emit OwnershipTransferred(_owner, newOwner);
              _owner = newOwner;
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.8.0;
      /*
       * @dev Provides information about the current execution context, including the
       * sender of the transaction and its data. While these are generally available
       * via msg.sender and msg.data, they should not be accessed in such a direct
       * manner, since when dealing with meta-transactions the account sending and
       * paying for execution may not be the actual sender (as far as an application
       * is concerned).
       *
       * This contract is only required for intermediate, library-like contracts.
       */
      abstract contract Context {
          function _msgSender() internal view virtual returns (address) {
              return msg.sender;
          }
          function _msgData() internal view virtual returns (bytes calldata) {
              this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
              return msg.data;
          }
      }
      

      File 2 of 2: Token
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.8.0) (access/AccessControl.sol)
      pragma solidity ^0.8.0;
      import "./IAccessControl.sol";
      import "../utils/Context.sol";
      import "../utils/Strings.sol";
      import "../utils/introspection/ERC165.sol";
      /**
       * @dev Contract module that allows children to implement role-based access
       * control mechanisms. This is a lightweight version that doesn't allow enumerating role
       * members except through off-chain means by accessing the contract event logs. Some
       * applications may benefit from on-chain enumerability, for those cases see
       * {AccessControlEnumerable}.
       *
       * Roles are referred to by their `bytes32` identifier. These should be exposed
       * in the external API and be unique. The best way to achieve this is by
       * using `public constant` hash digests:
       *
       * ```
       * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
       * ```
       *
       * Roles can be used to represent a set of permissions. To restrict access to a
       * function call, use {hasRole}:
       *
       * ```
       * function foo() public {
       *     require(hasRole(MY_ROLE, msg.sender));
       *     ...
       * }
       * ```
       *
       * Roles can be granted and revoked dynamically via the {grantRole} and
       * {revokeRole} functions. Each role has an associated admin role, and only
       * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
       *
       * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
       * that only accounts with this role will be able to grant or revoke other
       * roles. More complex role relationships can be created by using
       * {_setRoleAdmin}.
       *
       * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
       * grant and revoke this role. Extra precautions should be taken to secure
       * accounts that have been granted it.
       */
      abstract contract AccessControl is Context, IAccessControl, ERC165 {
          struct RoleData {
              mapping(address => bool) members;
              bytes32 adminRole;
          }
          mapping(bytes32 => RoleData) private _roles;
          bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;
          /**
           * @dev Modifier that checks that an account has a specific role. Reverts
           * with a standardized message including the required role.
           *
           * The format of the revert reason is given by the following regular expression:
           *
           *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
           *
           * _Available since v4.1._
           */
          modifier onlyRole(bytes32 role) {
              _checkRole(role);
              _;
          }
          /**
           * @dev See {IERC165-supportsInterface}.
           */
          function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
              return interfaceId == type(IAccessControl).interfaceId || super.supportsInterface(interfaceId);
          }
          /**
           * @dev Returns `true` if `account` has been granted `role`.
           */
          function hasRole(bytes32 role, address account) public view virtual override returns (bool) {
              return _roles[role].members[account];
          }
          /**
           * @dev Revert with a standard message if `_msgSender()` is missing `role`.
           * Overriding this function changes the behavior of the {onlyRole} modifier.
           *
           * Format of the revert message is described in {_checkRole}.
           *
           * _Available since v4.6._
           */
          function _checkRole(bytes32 role) internal view virtual {
              _checkRole(role, _msgSender());
          }
          /**
           * @dev Revert with a standard message if `account` is missing `role`.
           *
           * The format of the revert reason is given by the following regular expression:
           *
           *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
           */
          function _checkRole(bytes32 role, address account) internal view virtual {
              if (!hasRole(role, account)) {
                  revert(
                      string(
                          abi.encodePacked(
                              "AccessControl: account ",
                              Strings.toHexString(account),
                              " is missing role ",
                              Strings.toHexString(uint256(role), 32)
                          )
                      )
                  );
              }
          }
          /**
           * @dev Returns the admin role that controls `role`. See {grantRole} and
           * {revokeRole}.
           *
           * To change a role's admin, use {_setRoleAdmin}.
           */
          function getRoleAdmin(bytes32 role) public view virtual override returns (bytes32) {
              return _roles[role].adminRole;
          }
          /**
           * @dev Grants `role` to `account`.
           *
           * If `account` had not been already granted `role`, emits a {RoleGranted}
           * event.
           *
           * Requirements:
           *
           * - the caller must have ``role``'s admin role.
           *
           * May emit a {RoleGranted} event.
           */
          function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
              _grantRole(role, account);
          }
          /**
           * @dev Revokes `role` from `account`.
           *
           * If `account` had been granted `role`, emits a {RoleRevoked} event.
           *
           * Requirements:
           *
           * - the caller must have ``role``'s admin role.
           *
           * May emit a {RoleRevoked} event.
           */
          function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
              _revokeRole(role, account);
          }
          /**
           * @dev Revokes `role` from the calling account.
           *
           * Roles are often managed via {grantRole} and {revokeRole}: this function's
           * purpose is to provide a mechanism for accounts to lose their privileges
           * if they are compromised (such as when a trusted device is misplaced).
           *
           * If the calling account had been revoked `role`, emits a {RoleRevoked}
           * event.
           *
           * Requirements:
           *
           * - the caller must be `account`.
           *
           * May emit a {RoleRevoked} event.
           */
          function renounceRole(bytes32 role, address account) public virtual override {
              require(account == _msgSender(), "AccessControl: can only renounce roles for self");
              _revokeRole(role, account);
          }
          /**
           * @dev Grants `role` to `account`.
           *
           * If `account` had not been already granted `role`, emits a {RoleGranted}
           * event. Note that unlike {grantRole}, this function doesn't perform any
           * checks on the calling account.
           *
           * May emit a {RoleGranted} event.
           *
           * [WARNING]
           * ====
           * This function should only be called from the constructor when setting
           * up the initial roles for the system.
           *
           * Using this function in any other way is effectively circumventing the admin
           * system imposed by {AccessControl}.
           * ====
           *
           * NOTE: This function is deprecated in favor of {_grantRole}.
           */
          function _setupRole(bytes32 role, address account) internal virtual {
              _grantRole(role, account);
          }
          /**
           * @dev Sets `adminRole` as ``role``'s admin role.
           *
           * Emits a {RoleAdminChanged} event.
           */
          function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
              bytes32 previousAdminRole = getRoleAdmin(role);
              _roles[role].adminRole = adminRole;
              emit RoleAdminChanged(role, previousAdminRole, adminRole);
          }
          /**
           * @dev Grants `role` to `account`.
           *
           * Internal function without access restriction.
           *
           * May emit a {RoleGranted} event.
           */
          function _grantRole(bytes32 role, address account) internal virtual {
              if (!hasRole(role, account)) {
                  _roles[role].members[account] = true;
                  emit RoleGranted(role, account, _msgSender());
              }
          }
          /**
           * @dev Revokes `role` from `account`.
           *
           * Internal function without access restriction.
           *
           * May emit a {RoleRevoked} event.
           */
          function _revokeRole(bytes32 role, address account) internal virtual {
              if (hasRole(role, account)) {
                  _roles[role].members[account] = false;
                  emit RoleRevoked(role, account, _msgSender());
              }
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts v4.4.1 (access/IAccessControl.sol)
      pragma solidity ^0.8.0;
      /**
       * @dev External interface of AccessControl declared to support ERC165 detection.
       */
      interface IAccessControl {
          /**
           * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
           *
           * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
           * {RoleAdminChanged} not being emitted signaling this.
           *
           * _Available since v3.1._
           */
          event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);
          /**
           * @dev Emitted when `account` is granted `role`.
           *
           * `sender` is the account that originated the contract call, an admin role
           * bearer except when using {AccessControl-_setupRole}.
           */
          event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);
          /**
           * @dev Emitted when `account` is revoked `role`.
           *
           * `sender` is the account that originated the contract call:
           *   - if using `revokeRole`, it is the admin role bearer
           *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
           */
          event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);
          /**
           * @dev Returns `true` if `account` has been granted `role`.
           */
          function hasRole(bytes32 role, address account) external view returns (bool);
          /**
           * @dev Returns the admin role that controls `role`. See {grantRole} and
           * {revokeRole}.
           *
           * To change a role's admin, use {AccessControl-_setRoleAdmin}.
           */
          function getRoleAdmin(bytes32 role) external view returns (bytes32);
          /**
           * @dev Grants `role` to `account`.
           *
           * If `account` had not been already granted `role`, emits a {RoleGranted}
           * event.
           *
           * Requirements:
           *
           * - the caller must have ``role``'s admin role.
           */
          function grantRole(bytes32 role, address account) external;
          /**
           * @dev Revokes `role` from `account`.
           *
           * If `account` had been granted `role`, emits a {RoleRevoked} event.
           *
           * Requirements:
           *
           * - the caller must have ``role``'s admin role.
           */
          function revokeRole(bytes32 role, address account) external;
          /**
           * @dev Revokes `role` from the calling account.
           *
           * Roles are often managed via {grantRole} and {revokeRole}: this function's
           * purpose is to provide a mechanism for accounts to lose their privileges
           * if they are compromised (such as when a trusted device is misplaced).
           *
           * If the calling account had been granted `role`, emits a {RoleRevoked}
           * event.
           *
           * Requirements:
           *
           * - the caller must be `account`.
           */
          function renounceRole(bytes32 role, address account) external;
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)
      pragma solidity ^0.8.0;
      import "../utils/Context.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 Ownable is Context {
          address private _owner;
          event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
          /**
           * @dev Initializes the contract setting the deployer as the initial owner.
           */
          constructor() {
              _transferOwnership(_msgSender());
          }
          /**
           * @dev Throws if called by any account other than the owner.
           */
          modifier onlyOwner() {
              _checkOwner();
              _;
          }
          /**
           * @dev Returns the address of the current owner.
           */
          function owner() public view virtual returns (address) {
              return _owner;
          }
          /**
           * @dev Throws if the sender is not the owner.
           */
          function _checkOwner() internal view virtual {
              require(owner() == _msgSender(), "Ownable: caller is not the owner");
          }
          /**
           * @dev Leaves the contract without owner. It will not be possible to call
           * `onlyOwner` functions anymore. Can only be called by the current owner.
           *
           * NOTE: Renouncing ownership will leave the contract without an owner,
           * thereby removing any functionality that is only available to the owner.
           */
          function renounceOwnership() public virtual onlyOwner {
              _transferOwnership(address(0));
          }
          /**
           * @dev Transfers ownership of the contract to a new account (`newOwner`).
           * Can only be called by the current owner.
           */
          function transferOwnership(address newOwner) public virtual onlyOwner {
              require(newOwner != address(0), "Ownable: new owner is the zero address");
              _transferOwnership(newOwner);
          }
          /**
           * @dev Transfers ownership of the contract to a new account (`newOwner`).
           * Internal function without access restriction.
           */
          function _transferOwnership(address newOwner) internal virtual {
              address oldOwner = _owner;
              _owner = newOwner;
              emit OwnershipTransferred(oldOwner, newOwner);
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.7.0) (security/Pausable.sol)
      pragma solidity ^0.8.0;
      import "../utils/Context.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 Pausable is Context {
          /**
           * @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.
           */
          constructor() {
              _paused = false;
          }
          /**
           * @dev Modifier to make a function callable only when the contract is not paused.
           *
           * Requirements:
           *
           * - The contract must not be paused.
           */
          modifier whenNotPaused() {
              _requireNotPaused();
              _;
          }
          /**
           * @dev Modifier to make a function callable only when the contract is paused.
           *
           * Requirements:
           *
           * - The contract must be paused.
           */
          modifier whenPaused() {
              _requirePaused();
              _;
          }
          /**
           * @dev Returns true if the contract is paused, and false otherwise.
           */
          function paused() public view virtual returns (bool) {
              return _paused;
          }
          /**
           * @dev Throws if the contract is paused.
           */
          function _requireNotPaused() internal view virtual {
              require(!paused(), "Pausable: paused");
          }
          /**
           * @dev Throws if the contract is not paused.
           */
          function _requirePaused() internal view virtual {
              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());
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)
      pragma solidity ^0.8.0;
      import "../IERC721.sol";
      /**
       * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
       * @dev See https://eips.ethereum.org/EIPS/eip-721
       */
      interface IERC721Metadata is IERC721 {
          /**
           * @dev Returns the token collection name.
           */
          function name() external view returns (string memory);
          /**
           * @dev Returns the token collection symbol.
           */
          function symbol() external view returns (string memory);
          /**
           * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
           */
          function tokenURI(uint256 tokenId) external view returns (string memory);
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.8.0) (token/ERC721/IERC721.sol)
      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`.
           *
           * 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;
          /**
           * @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 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: Note that the caller is responsible to confirm that the recipient is capable of receiving ERC721
           * or else they may be permanently lost. Usage of {safeTransferFrom} prevents loss, though the caller must
           * understand this adds an external call which potentially creates a reentrancy vulnerability.
           *
           * 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 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 the account approved for `tokenId` token.
           *
           * Requirements:
           *
           * - `tokenId` must exist.
           */
          function getApproved(uint256 tokenId) external view returns (address operator);
          /**
           * @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);
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721Receiver.sol)
      pragma solidity ^0.8.0;
      /**
       * @title ERC721 token receiver interface
       * @dev Interface for any contract that wants to support safeTransfers
       * from ERC721 asset contracts.
       */
      interface IERC721Receiver {
          /**
           * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
           * by `operator` from `from`, this function is called.
           *
           * It must return its Solidity selector to confirm the token transfer.
           * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
           *
           * The selector can be obtained in Solidity with `IERC721Receiver.onERC721Received.selector`.
           */
          function onERC721Received(
              address operator,
              address from,
              uint256 tokenId,
              bytes calldata data
          ) external returns (bytes4);
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)
      pragma solidity ^0.8.1;
      /**
       * @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
           * ====
           *
           * [IMPORTANT]
           * ====
           * You shouldn't rely on `isContract` to protect against flash loan attacks!
           *
           * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
           * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
           * constructor.
           * ====
           */
          function isContract(address account) internal view returns (bool) {
              // This method relies on extcodesize/address.code.length, which returns 0
              // for contracts in construction, since the code is only stored at the end
              // of the constructor execution.
              return account.code.length > 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 functionCallWithValue(target, data, 0, "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");
              (bool success, bytes memory returndata) = target.call{value: value}(data);
              return verifyCallResultFromTarget(target, 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) {
              (bool success, bytes memory returndata) = target.staticcall(data);
              return verifyCallResultFromTarget(target, 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) {
              (bool success, bytes memory returndata) = target.delegatecall(data);
              return verifyCallResultFromTarget(target, success, returndata, errorMessage);
          }
          /**
           * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
           * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
           *
           * _Available since v4.8._
           */
          function verifyCallResultFromTarget(
              address target,
              bool success,
              bytes memory returndata,
              string memory errorMessage
          ) internal view returns (bytes memory) {
              if (success) {
                  if (returndata.length == 0) {
                      // only check isContract if the call was successful and the return data is empty
                      // otherwise we already know that it was a contract
                      require(isContract(target), "Address: call to non-contract");
                  }
                  return returndata;
              } else {
                  _revert(returndata, errorMessage);
              }
          }
          /**
           * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
           * revert reason or using the provided one.
           *
           * _Available since v4.3._
           */
          function verifyCallResult(
              bool success,
              bytes memory returndata,
              string memory errorMessage
          ) internal pure returns (bytes memory) {
              if (success) {
                  return returndata;
              } else {
                  _revert(returndata, errorMessage);
              }
          }
          function _revert(bytes memory returndata, string memory errorMessage) private pure {
              // 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
                  /// @solidity memory-safe-assembly
                  assembly {
                      let returndata_size := mload(returndata)
                      revert(add(32, returndata), returndata_size)
                  }
              } else {
                  revert(errorMessage);
              }
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
      pragma solidity ^0.8.0;
      /**
       * @dev Provides information about the current execution context, including the
       * sender of the transaction and its data. While these are generally available
       * via msg.sender and msg.data, they should not be accessed in such a direct
       * manner, since when dealing with meta-transactions the account sending and
       * paying for execution may not be the actual sender (as far as an application
       * is concerned).
       *
       * This contract is only required for intermediate, library-like contracts.
       */
      abstract contract Context {
          function _msgSender() internal view virtual returns (address) {
              return msg.sender;
          }
          function _msgData() internal view virtual returns (bytes calldata) {
              return msg.data;
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)
      pragma solidity ^0.8.0;
      import "./IERC165.sol";
      /**
       * @dev Implementation of the {IERC165} interface.
       *
       * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
       * for the additional interface id that will be supported. For example:
       *
       * ```solidity
       * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
       *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
       * }
       * ```
       *
       * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
       */
      abstract contract ERC165 is IERC165 {
          /**
           * @dev See {IERC165-supportsInterface}.
           */
          function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
              return interfaceId == type(IERC165).interfaceId;
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)
      pragma solidity ^0.8.0;
      /**
       * @dev Interface of the ERC165 standard, as defined in the
       * https://eips.ethereum.org/EIPS/eip-165[EIP].
       *
       * Implementers can declare support of contract interfaces, which can then be
       * queried by others ({ERC165Checker}).
       *
       * For an implementation, see {ERC165}.
       */
      interface IERC165 {
          /**
           * @dev Returns true if this contract implements the interface defined by
           * `interfaceId`. See the corresponding
           * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
           * to learn more about how these ids are created.
           *
           * This function call must use less than 30 000 gas.
           */
          function supportsInterface(bytes4 interfaceId) external view returns (bool);
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.8.0) (utils/math/Math.sol)
      pragma solidity ^0.8.0;
      /**
       * @dev Standard math utilities missing in the Solidity language.
       */
      library Math {
          enum Rounding {
              Down, // Toward negative infinity
              Up, // Toward infinity
              Zero // Toward zero
          }
          /**
           * @dev Returns the largest of two numbers.
           */
          function max(uint256 a, uint256 b) internal pure returns (uint256) {
              return a > b ? a : b;
          }
          /**
           * @dev Returns the smallest of two numbers.
           */
          function min(uint256 a, uint256 b) internal pure returns (uint256) {
              return a < b ? a : b;
          }
          /**
           * @dev Returns the average of two numbers. The result is rounded towards
           * zero.
           */
          function average(uint256 a, uint256 b) internal pure returns (uint256) {
              // (a + b) / 2 can overflow.
              return (a & b) + (a ^ b) / 2;
          }
          /**
           * @dev Returns the ceiling of the division of two numbers.
           *
           * This differs from standard division with `/` in that it rounds up instead
           * of rounding down.
           */
          function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
              // (a + b - 1) / b can overflow on addition, so we distribute.
              return a == 0 ? 0 : (a - 1) / b + 1;
          }
          /**
           * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
           * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)
           * with further edits by Uniswap Labs also under MIT license.
           */
          function mulDiv(
              uint256 x,
              uint256 y,
              uint256 denominator
          ) internal pure returns (uint256 result) {
              unchecked {
                  // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
                  // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
                  // variables such that product = prod1 * 2^256 + prod0.
                  uint256 prod0; // Least significant 256 bits of the product
                  uint256 prod1; // Most significant 256 bits of the product
                  assembly {
                      let mm := mulmod(x, y, not(0))
                      prod0 := mul(x, y)
                      prod1 := sub(sub(mm, prod0), lt(mm, prod0))
                  }
                  // Handle non-overflow cases, 256 by 256 division.
                  if (prod1 == 0) {
                      return prod0 / denominator;
                  }
                  // Make sure the result is less than 2^256. Also prevents denominator == 0.
                  require(denominator > prod1);
                  ///////////////////////////////////////////////
                  // 512 by 256 division.
                  ///////////////////////////////////////////////
                  // Make division exact by subtracting the remainder from [prod1 prod0].
                  uint256 remainder;
                  assembly {
                      // Compute remainder using mulmod.
                      remainder := mulmod(x, y, denominator)
                      // Subtract 256 bit number from 512 bit number.
                      prod1 := sub(prod1, gt(remainder, prod0))
                      prod0 := sub(prod0, remainder)
                  }
                  // Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.
                  // See https://cs.stackexchange.com/q/138556/92363.
                  // Does not overflow because the denominator cannot be zero at this stage in the function.
                  uint256 twos = denominator & (~denominator + 1);
                  assembly {
                      // Divide denominator by twos.
                      denominator := div(denominator, twos)
                      // Divide [prod1 prod0] by twos.
                      prod0 := div(prod0, twos)
                      // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                      twos := add(div(sub(0, twos), twos), 1)
                  }
                  // Shift in bits from prod1 into prod0.
                  prod0 |= prod1 * twos;
                  // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
                  // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
                  // four bits. That is, denominator * inv = 1 mod 2^4.
                  uint256 inverse = (3 * denominator) ^ 2;
                  // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also works
                  // in modular arithmetic, doubling the correct bits in each step.
                  inverse *= 2 - denominator * inverse; // inverse mod 2^8
                  inverse *= 2 - denominator * inverse; // inverse mod 2^16
                  inverse *= 2 - denominator * inverse; // inverse mod 2^32
                  inverse *= 2 - denominator * inverse; // inverse mod 2^64
                  inverse *= 2 - denominator * inverse; // inverse mod 2^128
                  inverse *= 2 - denominator * inverse; // inverse mod 2^256
                  // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
                  // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
                  // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
                  // is no longer required.
                  result = prod0 * inverse;
                  return result;
              }
          }
          /**
           * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
           */
          function mulDiv(
              uint256 x,
              uint256 y,
              uint256 denominator,
              Rounding rounding
          ) internal pure returns (uint256) {
              uint256 result = mulDiv(x, y, denominator);
              if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {
                  result += 1;
              }
              return result;
          }
          /**
           * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded down.
           *
           * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
           */
          function sqrt(uint256 a) internal pure returns (uint256) {
              if (a == 0) {
                  return 0;
              }
              // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
              //
              // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
              // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
              //
              // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
              // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
              // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
              //
              // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
              uint256 result = 1 << (log2(a) >> 1);
              // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
              // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
              // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
              // into the expected uint128 result.
              unchecked {
                  result = (result + a / result) >> 1;
                  result = (result + a / result) >> 1;
                  result = (result + a / result) >> 1;
                  result = (result + a / result) >> 1;
                  result = (result + a / result) >> 1;
                  result = (result + a / result) >> 1;
                  result = (result + a / result) >> 1;
                  return min(result, a / result);
              }
          }
          /**
           * @notice Calculates sqrt(a), following the selected rounding direction.
           */
          function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
              unchecked {
                  uint256 result = sqrt(a);
                  return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);
              }
          }
          /**
           * @dev Return the log in base 2, rounded down, of a positive value.
           * Returns 0 if given 0.
           */
          function log2(uint256 value) internal pure returns (uint256) {
              uint256 result = 0;
              unchecked {
                  if (value >> 128 > 0) {
                      value >>= 128;
                      result += 128;
                  }
                  if (value >> 64 > 0) {
                      value >>= 64;
                      result += 64;
                  }
                  if (value >> 32 > 0) {
                      value >>= 32;
                      result += 32;
                  }
                  if (value >> 16 > 0) {
                      value >>= 16;
                      result += 16;
                  }
                  if (value >> 8 > 0) {
                      value >>= 8;
                      result += 8;
                  }
                  if (value >> 4 > 0) {
                      value >>= 4;
                      result += 4;
                  }
                  if (value >> 2 > 0) {
                      value >>= 2;
                      result += 2;
                  }
                  if (value >> 1 > 0) {
                      result += 1;
                  }
              }
              return result;
          }
          /**
           * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
           * Returns 0 if given 0.
           */
          function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
              unchecked {
                  uint256 result = log2(value);
                  return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
              }
          }
          /**
           * @dev Return the log in base 10, rounded down, of a positive value.
           * Returns 0 if given 0.
           */
          function log10(uint256 value) internal pure returns (uint256) {
              uint256 result = 0;
              unchecked {
                  if (value >= 10**64) {
                      value /= 10**64;
                      result += 64;
                  }
                  if (value >= 10**32) {
                      value /= 10**32;
                      result += 32;
                  }
                  if (value >= 10**16) {
                      value /= 10**16;
                      result += 16;
                  }
                  if (value >= 10**8) {
                      value /= 10**8;
                      result += 8;
                  }
                  if (value >= 10**4) {
                      value /= 10**4;
                      result += 4;
                  }
                  if (value >= 10**2) {
                      value /= 10**2;
                      result += 2;
                  }
                  if (value >= 10**1) {
                      result += 1;
                  }
              }
              return result;
          }
          /**
           * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
           * Returns 0 if given 0.
           */
          function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
              unchecked {
                  uint256 result = log10(value);
                  return result + (rounding == Rounding.Up && 10**result < value ? 1 : 0);
              }
          }
          /**
           * @dev Return the log in base 256, rounded down, of a positive value.
           * Returns 0 if given 0.
           *
           * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
           */
          function log256(uint256 value) internal pure returns (uint256) {
              uint256 result = 0;
              unchecked {
                  if (value >> 128 > 0) {
                      value >>= 128;
                      result += 16;
                  }
                  if (value >> 64 > 0) {
                      value >>= 64;
                      result += 8;
                  }
                  if (value >> 32 > 0) {
                      value >>= 32;
                      result += 4;
                  }
                  if (value >> 16 > 0) {
                      value >>= 16;
                      result += 2;
                  }
                  if (value >> 8 > 0) {
                      result += 1;
                  }
              }
              return result;
          }
          /**
           * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
           * Returns 0 if given 0.
           */
          function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
              unchecked {
                  uint256 result = log256(value);
                  return result + (rounding == Rounding.Up && 1 << (result * 8) < value ? 1 : 0);
              }
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.8.0) (utils/Strings.sol)
      pragma solidity ^0.8.0;
      import "./math/Math.sol";
      /**
       * @dev String operations.
       */
      library Strings {
          bytes16 private constant _SYMBOLS = "0123456789abcdef";
          uint8 private constant _ADDRESS_LENGTH = 20;
          /**
           * @dev Converts a `uint256` to its ASCII `string` decimal representation.
           */
          function toString(uint256 value) internal pure returns (string memory) {
              unchecked {
                  uint256 length = Math.log10(value) + 1;
                  string memory buffer = new string(length);
                  uint256 ptr;
                  /// @solidity memory-safe-assembly
                  assembly {
                      ptr := add(buffer, add(32, length))
                  }
                  while (true) {
                      ptr--;
                      /// @solidity memory-safe-assembly
                      assembly {
                          mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
                      }
                      value /= 10;
                      if (value == 0) break;
                  }
                  return buffer;
              }
          }
          /**
           * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
           */
          function toHexString(uint256 value) internal pure returns (string memory) {
              unchecked {
                  return toHexString(value, Math.log256(value) + 1);
              }
          }
          /**
           * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
           */
          function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
              bytes memory buffer = new bytes(2 * length + 2);
              buffer[0] = "0";
              buffer[1] = "x";
              for (uint256 i = 2 * length + 1; i > 1; --i) {
                  buffer[i] = _SYMBOLS[value & 0xf];
                  value >>= 4;
              }
              require(value == 0, "Strings: hex length insufficient");
              return string(buffer);
          }
          /**
           * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
           */
          function toHexString(address addr) internal pure returns (string memory) {
              return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
          }
      }
      // contracts/Token.sol
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.8.4;
      import "erc721a/contracts/ERC721A.sol";
      import "@openzeppelin/contracts/security/Pausable.sol";
      import "@openzeppelin/contracts/access/AccessControl.sol";
      import "@openzeppelin/contracts/access/Ownable.sol";
      /*
      Ownable is used here only for implementing the interface required by some marketplaces
      Use AccessControl for controlling access
      */
      contract Token is ERC721A, Pausable, AccessControl, Ownable {
          bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
          string public baseURI;
          uint64 public totalTokens;
          uint64 public tokenReserve;
          event Mint(address indexed _to, uint256 indexed _tokenId, uint256 _setId, uint256 _option);
          event ChangeTotalTokens(uint64 _totalTokens);
          event ChangeTokenReserve(uint64 _tokenReserve);
          event ChangeBaseURI(string _baseURI);
          constructor(
              string memory _tokenName,
              string memory _tokenSymbol,
              string memory _uri,
              uint64 _totalTokens,
              uint32 _tokenReserve
          ) ERC721A(_tokenName, _tokenSymbol) {
              _setupRole(DEFAULT_ADMIN_ROLE, owner());
              totalTokens = _totalTokens;
              tokenReserve = _tokenReserve;
              baseURI = _uri;
          }
          function setAdmin(address _newAdmin) external onlyRole(DEFAULT_ADMIN_ROLE) {
              require(_newAdmin != address(0), 'empty address');
              _grantRole(DEFAULT_ADMIN_ROLE, _newAdmin);
              _revokeRole(DEFAULT_ADMIN_ROLE, msg.sender);
              _transferOwnership(_newAdmin);
          }
          function setTotalTokens(uint64 _totalTokens) external onlyRole(DEFAULT_ADMIN_ROLE) {
              totalTokens = _totalTokens;
              emit ChangeTotalTokens(_totalTokens);
          }
          function setTokenReserve(uint64 _tokenReserve) external onlyRole(DEFAULT_ADMIN_ROLE) {
              tokenReserve = _tokenReserve;
              emit ChangeTokenReserve(_tokenReserve);
          }
          function setBaseURI(string calldata _uri) external onlyRole(DEFAULT_ADMIN_ROLE) {
              baseURI = _uri;
              emit ChangeBaseURI(_uri);
          }
          function addMinter(address _minter) external onlyRole(DEFAULT_ADMIN_ROLE) {
              _grantRole(MINTER_ROLE, _minter);
          }
          function _baseURI() internal override view returns (string memory) {
              return baseURI;
          }
          function mint(address _owner, uint256 _amount, uint256 _setId, uint256[] calldata _options) external onlyRole(MINTER_ROLE) {
              uint256 oldTotalSupply = totalSupply();
              require(oldTotalSupply + _amount <= totalTokens - tokenReserve, "no supply left");
              require(_amount == _options.length, "not enough options");
              _safeMint(_owner, _amount);
              _emitMintEvents(_owner, oldTotalSupply, _amount, _setId, _options);
          }
          function minterMint(address _owner, uint256 _amount, uint256 _setId, uint256[] calldata _options) external onlyRole(MINTER_ROLE) {
              uint256 oldTotalSupply = totalSupply();
              require(oldTotalSupply + _amount <= totalTokens, "no supply left");
              require(_amount == _options.length, "not enough options");
              _safeMint(_owner, _amount);
              _emitMintEvents(_owner, oldTotalSupply, _amount, _setId, _options);
          }
          function pause() external onlyRole(DEFAULT_ADMIN_ROLE) {
              _pause();
          }
          function unPause() external onlyRole(DEFAULT_ADMIN_ROLE) {
              _unpause();
          }
          function adminBurn(uint256 _tokenId) external onlyRole(DEFAULT_ADMIN_ROLE) {
              _burn(_tokenId);
          }
          function burn(uint256 _tokenId) external {
              _burn(_tokenId, true);
          }
          function _beforeTokenTransfers(
              address from,
              address to,
              uint256 tokenId,
              uint256 quantity
          ) internal virtual override(ERC721A) {
              super._beforeTokenTransfers(from, to, tokenId, quantity);
          }
          function supportsInterface(bytes4 interfaceId) public view virtual override(ERC721A, AccessControl) returns (bool) {
              return super.supportsInterface(interfaceId);
          }
          function _emitMintEvents(address _to, uint256 _startTokenId, uint256 _amount, uint256 _setId, uint256[] calldata _options) internal {
              for (uint256 i = 0; i < _amount; i++) {
                  emit Mint(_to, i+_startTokenId, _setId, _options[i]);
              }
          }
      }// SPDX-License-Identifier: MIT
      // ERC721A Contracts v3.3.0
      // Creator: Chiru Labs
      pragma solidity ^0.8.4;
      import './IERC721A.sol';
      import '@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol';
      import '@openzeppelin/contracts/utils/Address.sol';
      import '@openzeppelin/contracts/utils/Context.sol';
      import '@openzeppelin/contracts/utils/Strings.sol';
      import '@openzeppelin/contracts/utils/introspection/ERC165.sol';
      /**
       * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
       * the Metadata extension. Built to optimize for lower gas during batch mints.
       *
       * Assumes serials are sequentially minted starting at _startTokenId() (defaults to 0, e.g. 0, 1, 2, 3..).
       *
       * Assumes that an owner cannot have more than 2**64 - 1 (max value of uint64) of supply.
       *
       * Assumes that the maximum token id cannot exceed 2**256 - 1 (max value of uint256).
       */
      contract ERC721A is Context, ERC165, IERC721A {
          using Address for address;
          using Strings for uint256;
          // The tokenId of the next token to be minted.
          uint256 internal _currentIndex;
          // The number of tokens burned.
          uint256 internal _burnCounter;
          // Token name
          string private _name;
          // Token symbol
          string private _symbol;
          // Mapping from token ID to ownership details
          // An empty struct value does not necessarily mean the token is unowned. See _ownershipOf implementation for details.
          mapping(uint256 => TokenOwnership) internal _ownerships;
          // Mapping owner address to address data
          mapping(address => AddressData) private _addressData;
          // Mapping from token ID to approved address
          mapping(uint256 => address) private _tokenApprovals;
          // Mapping from owner to operator approvals
          mapping(address => mapping(address => bool)) private _operatorApprovals;
          constructor(string memory name_, string memory symbol_) {
              _name = name_;
              _symbol = symbol_;
              _currentIndex = _startTokenId();
          }
          /**
           * To change the starting tokenId, please override this function.
           */
          function _startTokenId() internal view virtual returns (uint256) {
              return 0;
          }
          /**
           * @dev Burned tokens are calculated here, use _totalMinted() if you want to count just minted tokens.
           */
          function totalSupply() public view override returns (uint256) {
              // Counter underflow is impossible as _burnCounter cannot be incremented
              // more than _currentIndex - _startTokenId() times
              unchecked {
                  return _currentIndex - _burnCounter - _startTokenId();
              }
          }
          /**
           * Returns the total amount of tokens minted in the contract.
           */
          function _totalMinted() internal view returns (uint256) {
              // Counter underflow is impossible as _currentIndex does not decrement,
              // and it is initialized to _startTokenId()
              unchecked {
                  return _currentIndex - _startTokenId();
              }
          }
          /**
           * @dev See {IERC165-supportsInterface}.
           */
          function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
              return
                  interfaceId == type(IERC721).interfaceId ||
                  interfaceId == type(IERC721Metadata).interfaceId ||
                  super.supportsInterface(interfaceId);
          }
          /**
           * @dev See {IERC721-balanceOf}.
           */
          function balanceOf(address owner) public view override returns (uint256) {
              if (owner == address(0)) revert BalanceQueryForZeroAddress();
              return uint256(_addressData[owner].balance);
          }
          /**
           * Returns the number of tokens minted by `owner`.
           */
          function _numberMinted(address owner) internal view returns (uint256) {
              return uint256(_addressData[owner].numberMinted);
          }
          /**
           * Returns the number of tokens burned by or on behalf of `owner`.
           */
          function _numberBurned(address owner) internal view returns (uint256) {
              return uint256(_addressData[owner].numberBurned);
          }
          /**
           * Returns the auxillary data for `owner`. (e.g. number of whitelist mint slots used).
           */
          function _getAux(address owner) internal view returns (uint64) {
              return _addressData[owner].aux;
          }
          /**
           * Sets the auxillary data for `owner`. (e.g. number of whitelist mint slots used).
           * If there are multiple variables, please pack them into a uint64.
           */
          function _setAux(address owner, uint64 aux) internal {
              _addressData[owner].aux = aux;
          }
          /**
           * Gas spent here starts off proportional to the maximum mint batch size.
           * It gradually moves to O(1) as tokens get transferred around in the collection over time.
           */
          function _ownershipOf(uint256 tokenId) internal view returns (TokenOwnership memory) {
              uint256 curr = tokenId;
              unchecked {
                  if (_startTokenId() <= curr) if (curr < _currentIndex) {
                      TokenOwnership memory ownership = _ownerships[curr];
                      if (!ownership.burned) {
                          if (ownership.addr != address(0)) {
                              return ownership;
                          }
                          // Invariant:
                          // There will always be an ownership that has an address and is not burned
                          // before an ownership that does not have an address and is not burned.
                          // Hence, curr will not underflow.
                          while (true) {
                              curr--;
                              ownership = _ownerships[curr];
                              if (ownership.addr != address(0)) {
                                  return ownership;
                              }
                          }
                      }
                  }
              }
              revert OwnerQueryForNonexistentToken();
          }
          /**
           * @dev See {IERC721-ownerOf}.
           */
          function ownerOf(uint256 tokenId) public view override returns (address) {
              return _ownershipOf(tokenId).addr;
          }
          /**
           * @dev See {IERC721Metadata-name}.
           */
          function name() public view virtual override returns (string memory) {
              return _name;
          }
          /**
           * @dev See {IERC721Metadata-symbol}.
           */
          function symbol() public view virtual override returns (string memory) {
              return _symbol;
          }
          /**
           * @dev See {IERC721Metadata-tokenURI}.
           */
          function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
              if (!_exists(tokenId)) revert URIQueryForNonexistentToken();
              string memory baseURI = _baseURI();
              return bytes(baseURI).length != 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : '';
          }
          /**
           * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
           * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
           * by default, can be overriden in child contracts.
           */
          function _baseURI() internal view virtual returns (string memory) {
              return '';
          }
          /**
           * @dev See {IERC721-approve}.
           */
          function approve(address to, uint256 tokenId) public override {
              address owner = ERC721A.ownerOf(tokenId);
              if (to == owner) revert ApprovalToCurrentOwner();
              if (_msgSender() != owner) if(!isApprovedForAll(owner, _msgSender())) {
                  revert ApprovalCallerNotOwnerNorApproved();
              }
              _approve(to, tokenId, owner);
          }
          /**
           * @dev See {IERC721-getApproved}.
           */
          function getApproved(uint256 tokenId) public view override returns (address) {
              if (!_exists(tokenId)) revert ApprovalQueryForNonexistentToken();
              return _tokenApprovals[tokenId];
          }
          /**
           * @dev See {IERC721-setApprovalForAll}.
           */
          function setApprovalForAll(address operator, bool approved) public virtual override {
              if (operator == _msgSender()) revert ApproveToCaller();
              _operatorApprovals[_msgSender()][operator] = approved;
              emit ApprovalForAll(_msgSender(), operator, approved);
          }
          /**
           * @dev See {IERC721-isApprovedForAll}.
           */
          function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
              return _operatorApprovals[owner][operator];
          }
          /**
           * @dev See {IERC721-transferFrom}.
           */
          function transferFrom(
              address from,
              address to,
              uint256 tokenId
          ) public virtual override {
              _transfer(from, to, tokenId);
          }
          /**
           * @dev See {IERC721-safeTransferFrom}.
           */
          function safeTransferFrom(
              address from,
              address to,
              uint256 tokenId
          ) public virtual override {
              safeTransferFrom(from, to, tokenId, '');
          }
          /**
           * @dev See {IERC721-safeTransferFrom}.
           */
          function safeTransferFrom(
              address from,
              address to,
              uint256 tokenId,
              bytes memory _data
          ) public virtual override {
              _transfer(from, to, tokenId);
              if (to.isContract()) if(!_checkContractOnERC721Received(from, to, tokenId, _data)) {
                  revert TransferToNonERC721ReceiverImplementer();
              }
          }
          /**
           * @dev Returns whether `tokenId` exists.
           *
           * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
           *
           * Tokens start existing when they are minted (`_mint`),
           */
          function _exists(uint256 tokenId) internal view returns (bool) {
              return _startTokenId() <= tokenId && tokenId < _currentIndex && !_ownerships[tokenId].burned;
          }
          /**
           * @dev Equivalent to `_safeMint(to, quantity, '')`.
           */
          function _safeMint(address to, uint256 quantity) internal {
              _safeMint(to, quantity, '');
          }
          /**
           * @dev Safely mints `quantity` tokens and transfers them to `to`.
           *
           * Requirements:
           *
           * - If `to` refers to a smart contract, it must implement
           *   {IERC721Receiver-onERC721Received}, which is called for each safe transfer.
           * - `quantity` must be greater than 0.
           *
           * Emits a {Transfer} event.
           */
          function _safeMint(
              address to,
              uint256 quantity,
              bytes memory _data
          ) internal {
              uint256 startTokenId = _currentIndex;
              if (to == address(0)) revert MintToZeroAddress();
              if (quantity == 0) revert MintZeroQuantity();
              _beforeTokenTransfers(address(0), to, startTokenId, quantity);
              // Overflows are incredibly unrealistic.
              // balance or numberMinted overflow if current value of either + quantity > 1.8e19 (2**64) - 1
              // updatedIndex overflows if _currentIndex + quantity > 1.2e77 (2**256) - 1
              unchecked {
                  _addressData[to].balance += uint64(quantity);
                  _addressData[to].numberMinted += uint64(quantity);
                  _ownerships[startTokenId].addr = to;
                  _ownerships[startTokenId].startTimestamp = uint64(block.timestamp);
                  uint256 updatedIndex = startTokenId;
                  uint256 end = updatedIndex + quantity;
                  if (to.isContract()) {
                      do {
                          emit Transfer(address(0), to, updatedIndex);
                          if (!_checkContractOnERC721Received(address(0), to, updatedIndex++, _data)) {
                              revert TransferToNonERC721ReceiverImplementer();
                          }
                      } while (updatedIndex < end);
                      // Reentrancy protection
                      if (_currentIndex != startTokenId) revert();
                  } else {
                      do {
                          emit Transfer(address(0), to, updatedIndex++);
                      } while (updatedIndex < end);
                  }
                  _currentIndex = updatedIndex;
              }
              _afterTokenTransfers(address(0), to, startTokenId, quantity);
          }
          /**
           * @dev Mints `quantity` tokens and transfers them to `to`.
           *
           * Requirements:
           *
           * - `to` cannot be the zero address.
           * - `quantity` must be greater than 0.
           *
           * Emits a {Transfer} event.
           */
          function _mint(address to, uint256 quantity) internal {
              uint256 startTokenId = _currentIndex;
              if (to == address(0)) revert MintToZeroAddress();
              if (quantity == 0) revert MintZeroQuantity();
              _beforeTokenTransfers(address(0), to, startTokenId, quantity);
              // Overflows are incredibly unrealistic.
              // balance or numberMinted overflow if current value of either + quantity > 1.8e19 (2**64) - 1
              // updatedIndex overflows if _currentIndex + quantity > 1.2e77 (2**256) - 1
              unchecked {
                  _addressData[to].balance += uint64(quantity);
                  _addressData[to].numberMinted += uint64(quantity);
                  _ownerships[startTokenId].addr = to;
                  _ownerships[startTokenId].startTimestamp = uint64(block.timestamp);
                  uint256 updatedIndex = startTokenId;
                  uint256 end = updatedIndex + quantity;
                  do {
                      emit Transfer(address(0), to, updatedIndex++);
                  } while (updatedIndex < end);
                  _currentIndex = updatedIndex;
              }
              _afterTokenTransfers(address(0), to, startTokenId, quantity);
          }
          /**
           * @dev Transfers `tokenId` from `from` to `to`.
           *
           * Requirements:
           *
           * - `to` cannot be the zero address.
           * - `tokenId` token must be owned by `from`.
           *
           * Emits a {Transfer} event.
           */
          function _transfer(
              address from,
              address to,
              uint256 tokenId
          ) private {
              TokenOwnership memory prevOwnership = _ownershipOf(tokenId);
              if (prevOwnership.addr != from) revert TransferFromIncorrectOwner();
              bool isApprovedOrOwner = (_msgSender() == from ||
                  isApprovedForAll(from, _msgSender()) ||
                  getApproved(tokenId) == _msgSender());
              if (!isApprovedOrOwner) revert TransferCallerNotOwnerNorApproved();
              if (to == address(0)) revert TransferToZeroAddress();
              _beforeTokenTransfers(from, to, tokenId, 1);
              // Clear approvals from the previous owner
              _approve(address(0), tokenId, from);
              // Underflow of the sender's balance is impossible because we check for
              // ownership above and the recipient's balance can't realistically overflow.
              // Counter overflow is incredibly unrealistic as tokenId would have to be 2**256.
              unchecked {
                  _addressData[from].balance -= 1;
                  _addressData[to].balance += 1;
                  TokenOwnership storage currSlot = _ownerships[tokenId];
                  currSlot.addr = to;
                  currSlot.startTimestamp = uint64(block.timestamp);
                  // If the ownership slot of tokenId+1 is not explicitly set, that means the transfer initiator owns it.
                  // Set the slot of tokenId+1 explicitly in storage to maintain correctness for ownerOf(tokenId+1) calls.
                  uint256 nextTokenId = tokenId + 1;
                  TokenOwnership storage nextSlot = _ownerships[nextTokenId];
                  if (nextSlot.addr == address(0)) {
                      // This will suffice for checking _exists(nextTokenId),
                      // as a burned slot cannot contain the zero address.
                      if (nextTokenId != _currentIndex) {
                          nextSlot.addr = from;
                          nextSlot.startTimestamp = prevOwnership.startTimestamp;
                      }
                  }
              }
              emit Transfer(from, to, tokenId);
              _afterTokenTransfers(from, to, tokenId, 1);
          }
          /**
           * @dev Equivalent to `_burn(tokenId, false)`.
           */
          function _burn(uint256 tokenId) internal virtual {
              _burn(tokenId, false);
          }
          /**
           * @dev Destroys `tokenId`.
           * The approval is cleared when the token is burned.
           *
           * Requirements:
           *
           * - `tokenId` must exist.
           *
           * Emits a {Transfer} event.
           */
          function _burn(uint256 tokenId, bool approvalCheck) internal virtual {
              TokenOwnership memory prevOwnership = _ownershipOf(tokenId);
              address from = prevOwnership.addr;
              if (approvalCheck) {
                  bool isApprovedOrOwner = (_msgSender() == from ||
                      isApprovedForAll(from, _msgSender()) ||
                      getApproved(tokenId) == _msgSender());
                  if (!isApprovedOrOwner) revert TransferCallerNotOwnerNorApproved();
              }
              _beforeTokenTransfers(from, address(0), tokenId, 1);
              // Clear approvals from the previous owner
              _approve(address(0), tokenId, from);
              // Underflow of the sender's balance is impossible because we check for
              // ownership above and the recipient's balance can't realistically overflow.
              // Counter overflow is incredibly unrealistic as tokenId would have to be 2**256.
              unchecked {
                  AddressData storage addressData = _addressData[from];
                  addressData.balance -= 1;
                  addressData.numberBurned += 1;
                  // Keep track of who burned the token, and the timestamp of burning.
                  TokenOwnership storage currSlot = _ownerships[tokenId];
                  currSlot.addr = from;
                  currSlot.startTimestamp = uint64(block.timestamp);
                  currSlot.burned = true;
                  // If the ownership slot of tokenId+1 is not explicitly set, that means the burn initiator owns it.
                  // Set the slot of tokenId+1 explicitly in storage to maintain correctness for ownerOf(tokenId+1) calls.
                  uint256 nextTokenId = tokenId + 1;
                  TokenOwnership storage nextSlot = _ownerships[nextTokenId];
                  if (nextSlot.addr == address(0)) {
                      // This will suffice for checking _exists(nextTokenId),
                      // as a burned slot cannot contain the zero address.
                      if (nextTokenId != _currentIndex) {
                          nextSlot.addr = from;
                          nextSlot.startTimestamp = prevOwnership.startTimestamp;
                      }
                  }
              }
              emit Transfer(from, address(0), tokenId);
              _afterTokenTransfers(from, address(0), tokenId, 1);
              // Overflow not possible, as _burnCounter cannot be exceed _currentIndex times.
              unchecked {
                  _burnCounter++;
              }
          }
          /**
           * @dev Approve `to` to operate on `tokenId`
           *
           * Emits a {Approval} event.
           */
          function _approve(
              address to,
              uint256 tokenId,
              address owner
          ) private {
              _tokenApprovals[tokenId] = to;
              emit Approval(owner, to, tokenId);
          }
          /**
           * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target contract.
           *
           * @param from address representing the previous owner of the given token ID
           * @param to target address that will receive the tokens
           * @param tokenId uint256 ID of the token to be transferred
           * @param _data bytes optional data to send along with the call
           * @return bool whether the call correctly returned the expected magic value
           */
          function _checkContractOnERC721Received(
              address from,
              address to,
              uint256 tokenId,
              bytes memory _data
          ) private returns (bool) {
              try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                  return retval == IERC721Receiver(to).onERC721Received.selector;
              } catch (bytes memory reason) {
                  if (reason.length == 0) {
                      revert TransferToNonERC721ReceiverImplementer();
                  } else {
                      assembly {
                          revert(add(32, reason), mload(reason))
                      }
                  }
              }
          }
          /**
           * @dev Hook that is called before a set of serially-ordered token ids are about to be transferred. This includes minting.
           * And also called before burning one token.
           *
           * startTokenId - the first token id to be transferred
           * quantity - the amount to be transferred
           *
           * Calling conditions:
           *
           * - When `from` and `to` are both non-zero, `from`'s `tokenId` will be
           * transferred to `to`.
           * - When `from` is zero, `tokenId` will be minted for `to`.
           * - When `to` is zero, `tokenId` will be burned by `from`.
           * - `from` and `to` are never both zero.
           */
          function _beforeTokenTransfers(
              address from,
              address to,
              uint256 startTokenId,
              uint256 quantity
          ) internal virtual {}
          /**
           * @dev Hook that is called after a set of serially-ordered token ids have been transferred. This includes
           * minting.
           * And also called after one token has been burned.
           *
           * startTokenId - the first token id to be transferred
           * quantity - the amount to be transferred
           *
           * Calling conditions:
           *
           * - When `from` and `to` are both non-zero, `from`'s `tokenId` has been
           * transferred to `to`.
           * - When `from` is zero, `tokenId` has been minted for `to`.
           * - When `to` is zero, `tokenId` has been burned by `from`.
           * - `from` and `to` are never both zero.
           */
          function _afterTokenTransfers(
              address from,
              address to,
              uint256 startTokenId,
              uint256 quantity
          ) internal virtual {}
      }
      // SPDX-License-Identifier: MIT
      // ERC721A Contracts v3.3.0
      // Creator: Chiru Labs
      pragma solidity ^0.8.4;
      import '@openzeppelin/contracts/token/ERC721/IERC721.sol';
      import '@openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol';
      /**
       * @dev Interface of an ERC721A compliant contract.
       */
      interface IERC721A is IERC721, IERC721Metadata {
          /**
           * The caller must own the token or be an approved operator.
           */
          error ApprovalCallerNotOwnerNorApproved();
          /**
           * The token does not exist.
           */
          error ApprovalQueryForNonexistentToken();
          /**
           * The caller cannot approve to their own address.
           */
          error ApproveToCaller();
          /**
           * The caller cannot approve to the current owner.
           */
          error ApprovalToCurrentOwner();
          /**
           * Cannot query the balance for the zero address.
           */
          error BalanceQueryForZeroAddress();
          /**
           * Cannot mint to the zero address.
           */
          error MintToZeroAddress();
          /**
           * The quantity of tokens minted must be more than zero.
           */
          error MintZeroQuantity();
          /**
           * The token does not exist.
           */
          error OwnerQueryForNonexistentToken();
          /**
           * The caller must own the token or be an approved operator.
           */
          error TransferCallerNotOwnerNorApproved();
          /**
           * The token must be owned by `from`.
           */
          error TransferFromIncorrectOwner();
          /**
           * Cannot safely transfer to a contract that does not implement the ERC721Receiver interface.
           */
          error TransferToNonERC721ReceiverImplementer();
          /**
           * Cannot transfer to the zero address.
           */
          error TransferToZeroAddress();
          /**
           * The token does not exist.
           */
          error URIQueryForNonexistentToken();
          // Compiler will pack this into a single 256bit word.
          struct TokenOwnership {
              // The address of the owner.
              address addr;
              // Keeps track of the start time of ownership with minimal overhead for tokenomics.
              uint64 startTimestamp;
              // Whether the token has been burned.
              bool burned;
          }
          // Compiler will pack this into a single 256bit word.
          struct AddressData {
              // Realistically, 2**64-1 is more than enough.
              uint64 balance;
              // Keeps track of mint count with minimal overhead for tokenomics.
              uint64 numberMinted;
              // Keeps track of burn count with minimal overhead for tokenomics.
              uint64 numberBurned;
              // For miscellaneous variable(s) pertaining to the address
              // (e.g. number of whitelist mint slots used).
              // If there are multiple variables, please pack them into a uint64.
              uint64 aux;
          }
          /**
           * @dev Returns the total amount of tokens stored by the contract.
           * 
           * Burned tokens are calculated here, use `_totalMinted()` if you want to count just minted tokens.
           */
          function totalSupply() external view returns (uint256);
      }