ETH Price: $2,128.89 (+1.46%)

Transaction Decoder

Block:
15468803 at Sep-04-2022 01:36:32 AM +UTC
Transaction Fee:
0.000565345373325096 ETH $1.20
Gas Used:
99,608 Gas / 5.675702487 Gwei

Emitted Events:

Account State Difference:

  Address   Before After State Difference Code
0x1Fec9354...E7b976227
0.032797831284321092 Eth
Nonce: 132
0.032232485910995996 Eth
Nonce: 133
0.000565345373325096
(Miner: 0x5dc...435)
3,149.030204128869399502 Eth3,149.030303736869399502 Eth0.000099608
0xF03c4e6b...C6E339120
0xFa7f908f...5EDb845af

Execution Trace

MasterCatsMint.mint( quantity=1 )
  • 0x784b2bf7e10ffdbe5647bac4ff71144d0be044c1.c884ef83( )
  • MasterCats.mintTo( quantity=[1], recipient=[0x1Fec9354b1ac1f470ba228a4de069CdE7b976227] )
    File 1 of 2: MasterCatsMint
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    import "@openzeppelin/contracts/utils/Address.sol";
    import './Delegated.sol';
    interface IERC20Withdraw{
      function balanceOf(address account) external view returns (uint256);
      function transfer(address to, uint256 amount) external returns (bool);
    }
    interface IERC721Withdraw{
      function transferFrom(address from, address to, uint256 tokenId) external;
    }
    interface IMasterCats{
      function mintTo(uint16[] calldata quantity, address[] calldata recipient) external payable;
    }
    interface IClaimed{
      function claimed( address ) external returns( uint );
    }
    contract MasterCatsMint is Delegated{
      struct MintConfig{
        uint64 ethPrice;
        uint16 freeMints;
        uint16 maxOrder;
        bool isMintActive;
        bool isFreeMintActive;
      }
      MintConfig public CONFIG = MintConfig(
        0.019 ether, //ethPrice
            1,
           10,
        false,
        false
      );
      IClaimed public CLAIMS = IClaimed(0x784b2Bf7e10FFdbE5647BAC4FF71144D0Be044c1);
      IMasterCats public PRINCIPAL = IMasterCats(0xF03c4e6b6187AcA96B18162CBb4468FC6E339120);
      string public name = "Master Cats Mint";
      string public symbol = "MCM";
      mapping(address => uint16) public claimed;
      constructor()
        Delegated(){
      }
      function mint( uint16 quantity ) external payable{
        MintConfig memory cfg = CONFIG;
        require( cfg.isMintActive, "sale is not active" );
        require( cfg.maxOrder >= quantity, "order too big" );
        ( uint16 paid, uint16 free, uint16 claims ) = calculateQuantities(msg.sender, quantity);
        require(msg.value >= paid * cfg.ethPrice, "insufficient funds" );
        if( free > 0 || claims > 0 ){
          claimed[ msg.sender ] = claims + free;
        }
        PRINCIPAL.mintTo{ value: msg.value }( _asArray( quantity ), _asArray( msg.sender ));
      }
      function setConfig( MintConfig calldata newConfig ) external onlyDelegates{
        CONFIG = newConfig;
      }
      function setPrincipal( IMasterCats newAddress ) external onlyDelegates{
        PRINCIPAL = newAddress;
      }
      //withdraw
      function withdraw() external onlyOwner {
        uint256 totalBalance = address(this).balance;
        require(totalBalance > 0, "no funds available");
        Address.sendValue(payable(owner()), totalBalance);
      }
      function withdraw(address token) external onlyDelegates{
        IERC20Withdraw erc20 = IERC20Withdraw(token);
        erc20.transfer(owner(), erc20.balanceOf(address(this)) );
      }
      function withdraw(address token, uint256[] calldata tokenId) external onlyDelegates{
        for( uint256 i = 0; i < tokenId.length; ++i ){
          IERC721Withdraw(token).transferFrom(address(this), owner(), tokenId[i] );
        }
      }
      function calculateQuantities( address account, uint16 quantity ) public returns( uint16, uint16, uint16 ){
        MintConfig memory cfg = CONFIG;
        //free mint is not active
        if( !cfg.isFreeMintActive )
          return (quantity, 0, 0);
        uint16 claims = claimed[ msg.sender ];
        if( claims == 0 && address(CLAIMS) != address(0)){
          claims = uint16(CLAIMS.claimed( account ));
        }
        //no free mints remaining
        if( claims >= cfg.freeMints )
          return (quantity, 0, claims);
        uint16 free = cfg.freeMints - claims;
        if( quantity > free ){
          //use remaining free
          uint16 paid = quantity - free;
          return (paid, free, claims);
        }
        else{
          //total quantity is free
          return (0, quantity, claims);
        }
      }
      function calculateTotal( address account, uint16 quantity ) external returns( uint256 ){
        ( uint16 paid, uint16 free, uint16 claims ) = calculateQuantities(account, quantity);
        return paid * CONFIG.ethPrice;
      }
      function _asArray(address element) private pure returns (address[] memory array) {
        array = new address[](1);
        array[0] = element;
      }
      function _asArray(uint16 element) private pure returns (uint16[] memory array) {
        array = new uint16[](1);
        array[0] = element;
      }
    }
    
    // SPDX-License-Identifier: MIT
    pragma solidity 0.8.9;
    import "@openzeppelin/contracts/access/Ownable.sol";
    contract Delegated is Ownable{
      mapping(address => bool) internal _delegates;
      modifier onlyDelegates {
        require(_delegates[msg.sender], "Invalid delegate" );
        _;
      }
      constructor()
        Ownable(){
        setDelegate( owner(), true );
      }
      //onlyOwner
      function isDelegate( address addr ) external view onlyOwner returns( bool ){
        return _delegates[addr];
      }
      function setDelegate( address addr, bool isDelegate_ ) public onlyOwner{
        _delegates[addr] = isDelegate_;
      }
      function transferOwnership(address newOwner) public virtual override onlyOwner {
        _delegates[newOwner] = true;
        super.transferOwnership( newOwner );
      }
    }
    // 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 (last updated v4.5.0) (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 functionCall(target, data, "Address: low-level call failed");
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
         * `errorMessage` as a fallback revert reason when `target` reverts.
         *
         * _Available since v3.1._
         */
        function functionCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal returns (bytes memory) {
            return functionCallWithValue(target, data, 0, errorMessage);
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
         * but also transferring `value` wei to `target`.
         *
         * Requirements:
         *
         * - the calling contract must have an ETH balance of at least `value`.
         * - the called Solidity function must be `payable`.
         *
         * _Available since v3.1._
         */
        function functionCallWithValue(
            address target,
            bytes memory data,
            uint256 value
        ) internal returns (bytes memory) {
            return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
        }
        /**
         * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
         * with `errorMessage` as a fallback revert reason when `target` reverts.
         *
         * _Available since v3.1._
         */
        function functionCallWithValue(
            address target,
            bytes memory data,
            uint256 value,
            string memory errorMessage
        ) internal returns (bytes memory) {
            require(address(this).balance >= value, "Address: insufficient balance for call");
            require(isContract(target), "Address: call to non-contract");
            (bool success, bytes memory returndata) = target.call{value: value}(data);
            return verifyCallResult(success, returndata, errorMessage);
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
         * but performing a static call.
         *
         * _Available since v3.3._
         */
        function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
            return functionStaticCall(target, data, "Address: low-level static call failed");
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
         * but performing a static call.
         *
         * _Available since v3.3._
         */
        function functionStaticCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal view returns (bytes memory) {
            require(isContract(target), "Address: static call to non-contract");
            (bool success, bytes memory returndata) = target.staticcall(data);
            return verifyCallResult(success, returndata, errorMessage);
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
         * but performing a delegate call.
         *
         * _Available since v3.4._
         */
        function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
            return functionDelegateCall(target, data, "Address: low-level delegate call failed");
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
         * but performing a delegate call.
         *
         * _Available since v3.4._
         */
        function functionDelegateCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal returns (bytes memory) {
            require(isContract(target), "Address: delegate call to non-contract");
            (bool success, bytes memory returndata) = target.delegatecall(data);
            return verifyCallResult(success, returndata, errorMessage);
        }
        /**
         * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
         * revert reason using the provided one.
         *
         * _Available since v4.3._
         */
        function verifyCallResult(
            bool success,
            bytes memory returndata,
            string memory errorMessage
        ) internal pure returns (bytes memory) {
            if (success) {
                return returndata;
            } else {
                // Look for revert reason and bubble it up if present
                if (returndata.length > 0) {
                    // The easiest way to bubble the revert reason is using memory via assembly
                    assembly {
                        let returndata_size := mload(returndata)
                        revert(add(32, returndata), returndata_size)
                    }
                } else {
                    revert(errorMessage);
                }
            }
        }
    }
    // SPDX-License-Identifier: MIT
    // OpenZeppelin Contracts v4.4.1 (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 Returns the address of the current owner.
         */
        function owner() public view virtual returns (address) {
            return _owner;
        }
        /**
         * @dev Throws if called by any account other than the owner.
         */
        modifier onlyOwner() {
            require(owner() == _msgSender(), "Ownable: caller is not the owner");
            _;
        }
        /**
         * @dev Leaves the contract without owner. It will not be possible to call
         * `onlyOwner` functions anymore. Can only be called by the current owner.
         *
         * NOTE: Renouncing ownership will leave the contract without an owner,
         * thereby removing any functionality that is only available to the owner.
         */
        function renounceOwnership() public virtual onlyOwner {
            _transferOwnership(address(0));
        }
        /**
         * @dev Transfers ownership of the contract to a new account (`newOwner`).
         * Can only be called by the current owner.
         */
        function transferOwnership(address newOwner) public virtual onlyOwner {
            require(newOwner != address(0), "Ownable: new owner is the zero address");
            _transferOwnership(newOwner);
        }
        /**
         * @dev Transfers ownership of the contract to a new account (`newOwner`).
         * Internal function without access restriction.
         */
        function _transferOwnership(address newOwner) internal virtual {
            address oldOwner = _owner;
            _owner = newOwner;
            emit OwnershipTransferred(oldOwner, newOwner);
        }
    }
    

    File 2 of 2: MasterCats
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    import "@openzeppelin/contracts/interfaces/IERC2981.sol";
    import "@openzeppelin/contracts/token/ERC1155/IERC1155.sol";
    import "@openzeppelin/contracts/utils/Strings.sol";
    import './Delegated.sol';
    import './ERC721Batch.sol';
    import './PaymentSplitterMod.sol';
    import './Signed.sol';
    interface IThe3030Badge{
      function balanceOf( address, uint ) external returns( uint );
      function burnFrom( address, uint[] calldata, uint[] calldata ) external payable;
    }
    contract MasterCats is Delegated, ERC721Batch, PaymentSplitterMod, Signed {
      using Strings for uint256;
      enum SaleState{
        NONE,   //0
        BADGE,  //1
        ALPHA,  //2
        _3,
        BETA,   //4
        _5,
        _6,
        _7,
        MAIN     //8
      }
      struct ClaimBalances{
        uint16 badge;
        uint16 alpha;
        uint16 beta;
        uint16 free;
      }
      struct MintConfig{
        uint64 ethPrice;
        uint16 freeMints;
        uint16 maxMint;
        uint16 maxOrder;
        uint16 maxSupply;
        uint8  saleState;
        bool isFreeMintActive;
      }
      MintConfig public CONFIG = MintConfig(
        0.07 ether, //ethPrice
           1,       //freeMints
        9000,       //maxMint
          10,       //maxOrder
        9000,       //maxSupply
        uint8(SaleState.NONE), //saleState
        false
      );
      IThe3030Badge public PRINCIPAL = IThe3030Badge( 0x01aFE4Ed0CFee364307a67Ec4EE28ebe480833C3 );
      string public tokenURIPrefix;
      string public tokenURISuffix;
      constructor()
        ERC721B("Master Cats", "MASTER" )
        Signed( 0x41C9E80FAa5E12Ac1d61549267fB497041f0EFb8 ){
        _addPayee( 0xed386149321FBd84f0c4e27a1701Ad05eCA32f8A, 32 ether );
        _addPayee( 0xf9467442d7f5c12283186101C80cd4a71497D7d5, 33 ether );
        _addPayee( 0x085FBF2d78308d2D69E9427d6D5eA774BCBC97AE, 15 ether );
        _addPayee( 0x4ba29e49F4EfeF6A4069e51545c31e4df634cdEA, 10 ether );
        _addPayee( 0x73b4c65d013c976cF774173FA3bd6f48Ec300419, 10 ether );
      }
      //view
      function getClaims( address account ) external returns( ClaimBalances memory balances ){
        require( address(PRINCIPAL) != address(0), "Invalid configuration" );
        MintConfig memory cfg = CONFIG;
        balances = ClaimBalances( 0, 0, 0, 0 );
        uint8 checkState = uint8(SaleState.BADGE);
        if( cfg.saleState & checkState == checkState ){
          balances.badge = uint16(PRINCIPAL.balanceOf( account, 0 ));
          if( balances.badge > owners[ account ].badges )
            balances.badge -= owners[ account ].badges;
          else
            balances.badge = 0;
        }
        checkState = uint8(SaleState.ALPHA);
        if( cfg.saleState & checkState == checkState )
          balances.alpha = uint16(PRINCIPAL.balanceOf( account, 1 ));
        checkState = uint8(SaleState.BETA);
        if( cfg.saleState & checkState == checkState )
          balances.beta = uint16(PRINCIPAL.balanceOf( account, 2 ));
        if( cfg.isFreeMintActive ){
          balances.free = CONFIG.freeMints;
          if( balances.free > owners[ account ].claimed )
            balances.free -= owners[ account ].claimed;
          else
            balances.free = 0;
        }
        return balances;
      }
      //view: IERC721Metadata
      function tokenURI( uint tokenId ) external view override returns( string memory ){
        require(_exists(tokenId), "query for nonexistent token");
        return string(abi.encodePacked(tokenURIPrefix, tokenId.toString(), tokenURISuffix));
      }
      function claim( uint16 badgeQty, uint16 alphaQty, uint16 betaQty, uint256[] calldata tokenIds, bytes calldata badgeSig ) external payable{
        MintConfig memory cfg = CONFIG;
        Owner memory prev = owners[msg.sender];
        if( badgeQty > 0 ){
          uint8 badgeState = uint8(SaleState.BADGE);
          require( cfg.saleState & badgeState == badgeState, "badge sale is disabled" );
          require( _isAuthorizedSigner( "1", badgeSig ), "not authorized for badge mints" );
          uint badgeBalance = PRINCIPAL.balanceOf( msg.sender, 0 );
          require( prev.badges + badgeQty <= badgeBalance, "all badges used" );
        }
        if( alphaQty > 0 ){
          uint8 alphaState = uint8(SaleState.ALPHA);
          require( cfg.saleState & alphaState == alphaState, "alpha sale is disabled" );
          PRINCIPAL.burnFrom( msg.sender, _asArray( 1 ), _asArray( alphaQty ) );
        }
        if( betaQty > 0 ){
          uint8 betaState = uint8(SaleState.BETA);
          require( cfg.saleState & betaState == betaState, "beta sale is disabled" );
          PRINCIPAL.burnFrom( msg.sender, _asArray( 2 ), _asArray( betaQty ) );
        }
        uint16 totalQuantity = badgeQty + alphaQty + betaQty;
        require( totalQuantity == tokenIds.length, "" );
        owners[msg.sender] = Owner(
          prev.balance + totalQuantity,
          prev.badges + badgeQty,
          prev.claimed,
          prev.purchased + totalQuantity
        );
        for(uint i; i < tokenIds.length; ++i){
          _mint( msg.sender, tokenIds[ i ] );
        }
      }
      //payable
      function mint( uint16 quantity ) external payable{
        MintConfig memory cfg = CONFIG;
        require( quantity > 0,                              "must order 1+" );
        require( quantity <= cfg.maxOrder,                  "order too big" );
        require( totalSupply() + quantity <= cfg.maxSupply, "mint/order exceeds supply" );
        uint8 mainState = uint8(SaleState.MAIN);
        require( cfg.saleState & mainState == mainState,    "sale is not active" );
        Owner memory prev = owners[msg.sender];
        require( prev.purchased + quantity <= cfg.maxMint,  "don't be greedy" );
        uint16 freeQty = 0;
        if( cfg.isFreeMintActive && cfg.freeMints > prev.claimed ){
          freeQty = cfg.freeMints - prev.claimed;
          if( quantity >= freeQty ){
            //use all free mints
            uint16 paidQty = quantity - freeQty;
            require( msg.value >= paidQty * cfg.ethPrice, "insufficient funds" );
          }
          else{
            freeQty = quantity;
          }
        }
        owners[msg.sender] = Owner(
          prev.balance + quantity,
          prev.badges,
          prev.claimed + freeQty,
          prev.purchased + quantity
        );
        for(uint i; i < quantity; ++i){
          _mint( msg.sender, _next() );
        }
      }
      //onlyDelegates
      function mintTo(uint16[] calldata quantity, address[] calldata recipient) external payable onlyDelegates{
        require(quantity.length == recipient.length, "Must provide equal quantities and recipients" );
        uint totalQuantity;
        uint supply = totalSupply();
        for(uint i; i < quantity.length; ++i){
          totalQuantity += quantity[i];
        }
        require( supply + totalQuantity <= CONFIG.maxSupply, "Mint/order exceeds supply" );
        for(uint i; i < recipient.length; ++i){
          for(uint j; j < quantity[i]; ++j){
            _mint( recipient[i], _next() );
          }
        }
      }
      function setConfig( MintConfig calldata config ) external onlyDelegates{
        CONFIG = config;
      }
      function setPrincipal( IThe3030Badge newPrincipal ) external onlyDelegates{
        PRINCIPAL = newPrincipal;
      }
      function setSigner( address newSigner ) external onlyDelegates{
        _setSigner( newSigner );
      }
      function setTokenURI( string calldata prefix, string calldata suffix ) external onlyDelegates{
        tokenURIPrefix = prefix;
        tokenURISuffix = suffix;
      }
      //onlyOwner
      function addPayee(address account, uint256 shares_) external onlyOwner {
        _addPayee( account, shares_ );
      }
      function resetCounters() external onlyOwner {
        _resetCounters();
      }
      function setPayee( uint index, address account, uint newShares ) external onlyOwner {
        _setPayee(index, account, newShares);
      }
      function _asArray(uint256 element) private pure returns (uint256[] memory array) {
        array = new uint256[](1);
        array[0] = element;
      }
    }
    
    // SPDX-License-Identifier: BSD-3
    pragma solidity ^0.8.0;
    import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
    contract Signed{
      using ECDSA for bytes32;
      address internal _signer;
      constructor( address signer ){
        _setSigner( signer );
      }
      function _createHash( string memory data ) internal virtual view returns ( bytes32 ){
        return keccak256( abi.encodePacked( address(this), msg.sender, data ) );
      }
      function _isAuthorizedSigner( string memory data, bytes calldata signature ) internal view virtual returns( bool ){
        return _signer == _recoverSigner( _createHash( data ), signature );
      }
      function _recoverSigner( bytes32 hashed, bytes memory signature ) internal pure returns( address ){
        return hashed.toEthSignedMessageHash().recover( signature );
      }
      function _setSigner( address signer ) internal{
        _signer = signer;
      }
    }
    
    // SPDX-License-Identifier: MIT
    pragma solidity 0.8.9;
    import "@openzeppelin/contracts/utils/Address.sol";
    import "@openzeppelin/contracts/utils/Context.sol";
    /**
     * @title PaymentSplitter
     * @dev This contract allows to split Ether payments among a group of accounts. The sender does not need to be aware
     * that the Ether will be split in this way, since it is handled transparently by the contract.
     *
     * The split can be in equal parts or in any other arbitrary proportion. The way this is specified is by assigning each
     * account to a number of shares. Of all the Ether that this contract receives, each account will then be able to claim
     * an amount proportional to the percentage of total shares they were assigned.
     *
     * `PaymentSplitter` follows a _pull payment_ model. This means that payments are not automatically forwarded to the
     * accounts but kept in this contract, and the actual transfer is triggered as a separate step by calling the {release}
     * function.
     */
    contract PaymentSplitterMod is Context {
        event PayeeAdded(address account, uint256 shares);
        event PaymentReleased(address to, uint256 amount);
        event PaymentReceived(address from, uint256 amount);
        uint256 private _totalShares;
        uint256 private _totalReleased;
        mapping(address => uint256) private _shares;
        mapping(address => uint256) private _released;
        address[] internal _payees;
        /**
         * @dev Creates an instance of `PaymentSplitter` where each account in `payees` is assigned the number of shares at
         * the matching position in the `shares` array.
         *
         * All addresses in `payees` must be non-zero. Both arrays must have the same non-zero length, and there must be no
         * duplicates in `payees`.
         */
        constructor() payable {}
        /**
         * @dev The Ether received will be logged with {PaymentReceived} events. Note that these events are not fully
         * reliable: it's possible for a contract to receive Ether without triggering this function. This only affects the
         * reliability of the events, and not the actual splitting of Ether.
         *
         * To learn more about this see the Solidity documentation for
         * https://solidity.readthedocs.io/en/latest/contracts.html#fallback-function[fallback
         * functions].
         */
        receive() external payable {
            emit PaymentReceived(_msgSender(), msg.value);
        }
        /**
         * @dev Getter for the total shares held by payees.
         */
        function totalShares() public view returns (uint256) {
            return _totalShares;
        }
        /**
         * @dev Getter for the total amount of Ether already released.
         */
        function totalReleased() public view returns (uint256) {
            return _totalReleased;
        }
        /**
         * @dev Getter for the amount of shares held by an account.
         */
        function shares(address account) public view returns (uint256) {
            return _shares[account];
        }
        /**
         * @dev Getter for the amount of Ether already released to a payee.
         */
        function released(address account) public view returns (uint256) {
            return _released[account];
        }
        /**
         * @dev Getter for the address of the payee number `index`.
         */
        function payee(uint256 index) public view returns (address) {
            return _payees[index];
        }
        /**
         * @dev Triggers a transfer to `account` of the amount of Ether they are owed, according to their percentage of the
         * total shares and their previous withdrawals.
         */
        function release(address payable account) public virtual {
            require(_shares[account] > 0, "PaymentSplitter: account has no shares");
            uint256 totalReceived = address(this).balance + _totalReleased;
            uint256 payment = (totalReceived * _shares[account]) / _totalShares - _released[account];
            require(payment != 0, "PaymentSplitter: account is not due payment");
            _released[account] = _released[account] + payment;
            _totalReleased = _totalReleased + payment;
            Address.sendValue(account, payment);
            emit PaymentReleased(account, payment);
        }
        function _addPayee(address account, uint256 shares_) internal {
            require(account != address(0), "PaymentSplitter: account is the zero address");
            require(shares_ > 0, "PaymentSplitter: shares are 0");
            require(_shares[account] == 0, "PaymentSplitter: account already has shares");
            _payees.push(account);
            _shares[account] = shares_;
            _totalShares = _totalShares + shares_;
            emit PayeeAdded(account, shares_);
        }
        function _resetCounters() internal {
            _totalReleased = 0;
            for(uint i; i < _payees.length; ++i ){
                _released[ _payees[i] ] = 0;
            }
        }
        function _setPayee( uint index, address account, uint newShares ) internal {
            _totalShares = _totalShares - _shares[ account ] + newShares;
            _shares[ account ] = newShares;
            _payees[ index ] = account;
        }
    }
    
    // SPDX-License-Identifier: MIT
    pragma solidity 0.8.9;
    interface IERC721Batch {
      function isOwnerOf( address account, uint[] calldata tokenIds ) external view returns( bool );
      function safeTransferBatch( address from, address to, uint[] calldata tokenIds, bytes calldata data ) external;
      function transferBatch( address from, address to, uint[] calldata tokenIds ) external;
      function walletOfOwner( address account ) external view returns( uint[] memory );
    }
    
    // SPDX-License-Identifier: MIT
    pragma solidity 0.8.9;
    import "@openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol";
    import "./ERC721B.sol";
    abstract contract ERC721EnumerableB is ERC721B, IERC721Enumerable {
      function supportsInterface( bytes4 interfaceId ) public view virtual override(IERC165, ERC721B) returns( bool ){
        return interfaceId == type(IERC721Enumerable).interfaceId || super.supportsInterface(interfaceId);
      }
      function tokenOfOwnerByIndex( address owner, uint256 index ) external view override returns( uint ){
        require( owners[ owner ].balance > index, "ERC721EnumerableB: owner index out of bounds" );
        uint256 count;
        uint256 tokenId;
        for( tokenId = range.lower; tokenId < range.upper; ++tokenId ){
          if( owner != tokens[tokenId].owner )
            continue;
          if( index == count++ )
            break;
        }
        return tokenId;
      }
      function tokenByIndex( uint256 index ) external view override returns( uint ){
        require( _exists( index ), "ERC721EnumerableB: query for nonexistent token");
        return index;
      }
      function totalSupply() public view virtual override( ERC721B, IERC721Enumerable ) returns( uint ){
        return super.totalSupply();
      }
    }
    
    // SPDX-License-Identifier: MIT
    pragma solidity 0.8.9;
    import "./IERC721Batch.sol";
    import "./ERC721EnumerableB.sol";
    abstract contract ERC721Batch is ERC721EnumerableB, IERC721Batch {
      function isOwnerOf( address account, uint[] calldata tokenIds ) external view override returns( bool ){
        for(uint i; i < tokenIds.length; ++i ){
          if( account != tokens[ tokenIds[i] ].owner )
            return false;
        }
        return true;
      }
      function safeTransferBatch( address from, address to, uint256[] calldata tokenIds, bytes calldata data ) external override{
        for(uint i; i < tokenIds.length; ++i ){
          safeTransferFrom( from, to, tokenIds[i], data );
        }
      }
      function transferBatch( address from, address to, uint256[] calldata tokenIds ) external override{
        for(uint i; i < tokenIds.length; ++i ){
          transferFrom( from, to, tokenIds[i] );
        }
      }
      function walletOfOwner( address account ) external view override returns( uint[] memory ){
        uint256 count;
        uint256 quantity = owners[ account ].balance;
        uint256[] memory wallet = new uint[]( quantity );
        for( uint i = range.lower; i < range.upper; ++i ){
          if( account == tokens[i].owner ){
            wallet[ count++ ] = i;
            if( count == quantity )
              break;
          }
        }
        return wallet;
      }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity 0.8.9;
    import "@openzeppelin/contracts/token/ERC721/IERC721.sol";
    import "@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol";
    import "@openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol";
    import "@openzeppelin/contracts/utils/Address.sol";
    import "@openzeppelin/contracts/utils/Context.sol";
    import "@openzeppelin/contracts/utils/introspection/ERC165.sol";
    abstract contract ERC721B is Context, ERC165, IERC721, IERC721Metadata {
      using Address for address;
      struct Owner{
        uint16 balance;
        uint16 badges;
        uint16 claimed;
        uint16 purchased;
      }
      struct TokenRange{
        uint16 burned;
        uint16 current;
        uint16 minted;
        uint16 lower;
        uint16 upper;
      }
      struct Token{
        address owner;
      }
      //Token[] public tokens;
      TokenRange public range;
      mapping(uint256 => Token) public tokens;
      mapping(address => Owner) public owners;
      string private _name;
      string private _symbol;
      mapping(uint256 => address) internal _tokenApprovals;
      mapping(address => mapping(address => bool)) private _operatorApprovals;
      constructor(string memory name_, string memory symbol_ ){
        _name = name_;
        _symbol = symbol_;
      }
      //public view
      function balanceOf(address owner) external view override returns( uint256 balance ){
        require(owner != address(0), "ERC721B: balance query for the zero address");
        return owners[owner].balance;
      }
      function name() external view override returns( string memory name_ ){
        return _name;
      }
      function ownerOf(uint256 tokenId) public view override returns( address owner ){
        require(_exists(tokenId), "ERC721B: query for nonexistent token");
        return tokens[tokenId].owner;
      }
      function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns( bool isSupported ){
        return
          interfaceId == type(IERC721).interfaceId ||
          interfaceId == type(IERC721Metadata).interfaceId ||
          super.supportsInterface(interfaceId);
      }
      function symbol() external view override returns( string memory symbol_ ){
        return _symbol;
      }
      function totalSupply() public view virtual returns( uint256 ){
        return range.minted - range.burned;
      }
      //approvals
      function approve(address to, uint256 tokenId) external override {
        address owner = ownerOf(tokenId);
        require(to != owner, "ERC721B: approval to current owner");
        require(
          _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
          "ERC721B: caller is not owner nor approved for all"
        );
        _approve(to, tokenId);
      }
      function getApproved(uint256 tokenId) public view override returns( address approver ){
        require(_exists(tokenId), "ERC721: query for nonexistent token");
        return _tokenApprovals[tokenId];
      }
      function isApprovedForAll(address owner, address operator) public view override returns( bool isApproved ){
        return _operatorApprovals[owner][operator];
      }
      function setApprovalForAll(address operator, bool approved) external override {
        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
      }
      //transfers
      function safeTransferFrom(address from, address to, uint256 tokenId) external override{
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721B: caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, "");
      }
      function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721B: caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, _data);
      }
      function transferFrom(address from, address to, uint256 tokenId) public override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721B: caller is not owner nor approved");
        _transfer(from, to, tokenId);
      }
      //internal
      function _approve(address to, uint256 tokenId) internal{
        _tokenApprovals[tokenId] = to;
        emit Approval(ownerOf(tokenId), to, tokenId);
      }
      function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual {
      }
      /*
      function _burn(address from, uint256 tokenId) internal {
        require(ownerOf(tokenId) == from, "ERC721B: burn of token that is not own");
        
        // Clear approvals
        delete _tokenApprovals[tokenId];
        _beforeTokenTransfer(from, address(0), tokenId);
        ++range.burned;
        --owners[ from ].balance;
        tokens[tokenId].owner = address(0);
        emit Transfer(from, address(0), tokenId);
      }
      */
      function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data) private returns( bool ){
        if (to.isContract()) {
          try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
            return retval == IERC721Receiver.onERC721Received.selector;
          } catch (bytes memory reason) {
            if (reason.length == 0) {
              revert("ERC721B: transfer to non ERC721Receiver implementer");
            } else {
              assembly {
                revert(add(32, reason), mload(reason))
              }
            }
          }
        } else {
          return true;
        }
      }
      function _exists(uint256 tokenId) internal view returns( bool ){
        return range.lower <= tokenId
          && tokenId < range.upper
          && tokens[tokenId].owner != address(0);
      }
      function _isApprovedOrOwner(address spender, uint256 tokenId) internal view returns( bool isApproved ){
        require(_exists(tokenId), "ERC721B: query for nonexistent token");
        address owner = ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
      }
      function _mint( address to, uint256 tokenId ) internal virtual{
        require(!_exists(tokenId), "ERC721B: mint for existing token");
        _beforeTokenTransfer(address(0), to, tokenId);
        _updateRange( tokenId );
        tokens[ tokenId ] = Token( to );
        emit Transfer( address(0), to, tokenId );
      }
      function _next() internal virtual returns(uint256 current){
        current = range.current;
        while( _exists( current ) ){
          ++current;
        }
        range.current = uint16( current );
      }
      function _safeTransfer(address from, address to, uint256 tokenId, bytes memory _data) internal{
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721B: transfer to non ERC721Receiver implementer");
      }
      function _transfer(address from, address to, uint256 tokenId) internal virtual {
        require(ownerOf(tokenId) == from, "ERC721B: transfer of token that is not own");
        // Clear approvals from the previous owner
        delete _tokenApprovals[tokenId];
        _beforeTokenTransfer(from, to, tokenId);
        unchecked {
          --owners[from].balance;
          ++owners[to].balance;
        }
        tokens[tokenId].owner = to;
        emit Transfer(from, to, tokenId);
      }
      function _updateRange(uint256 tokenId) private{
        TokenRange memory prev = range;
        ++prev.minted;
        if( tokenId <= prev.current ){
    //console.log( "_updateRange", tokenId, prev.current );
          ++prev.current;
        }
        if( tokenId > prev.upper )
          prev.upper = uint16(tokenId + 1);
        range = prev;
        /*
        range = TokenRange(
          prev.burned,
          prev.current,
          prev.minted,
          prev.lower,
          prev.upper
        );
        */
      }
    }
    
    // SPDX-License-Identifier: MIT
    pragma solidity 0.8.9;
    import "@openzeppelin/contracts/access/Ownable.sol";
    contract Delegated is Ownable{
      mapping(address => bool) internal _delegates;
      modifier onlyDelegates {
        require(_delegates[msg.sender], "Invalid delegate" );
        _;
      }
      constructor()
        Ownable(){
        setDelegate( owner(), true );
      }
      //onlyOwner
      function isDelegate( address addr ) external view onlyOwner returns( bool ){
        return _delegates[addr];
      }
      function setDelegate( address addr, bool isDelegate_ ) public onlyOwner{
        _delegates[addr] = isDelegate_;
      }
      function transferOwnership(address newOwner) public virtual override onlyOwner {
        _delegates[newOwner] = true;
        super.transferOwnership( newOwner );
      }
    }
    // 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 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 (last updated v4.5.0) (utils/cryptography/ECDSA.sol)
    pragma solidity ^0.8.0;
    import "../Strings.sol";
    /**
     * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
     *
     * These functions can be used to verify that a message was signed by the holder
     * of the private keys of a given address.
     */
    library ECDSA {
        enum RecoverError {
            NoError,
            InvalidSignature,
            InvalidSignatureLength,
            InvalidSignatureS,
            InvalidSignatureV
        }
        function _throwError(RecoverError error) private pure {
            if (error == RecoverError.NoError) {
                return; // no error: do nothing
            } else if (error == RecoverError.InvalidSignature) {
                revert("ECDSA: invalid signature");
            } else if (error == RecoverError.InvalidSignatureLength) {
                revert("ECDSA: invalid signature length");
            } else if (error == RecoverError.InvalidSignatureS) {
                revert("ECDSA: invalid signature 's' value");
            } else if (error == RecoverError.InvalidSignatureV) {
                revert("ECDSA: invalid signature 'v' value");
            }
        }
        /**
         * @dev Returns the address that signed a hashed message (`hash`) with
         * `signature` or error string. This address can then be used for verification purposes.
         *
         * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
         * this function rejects them by requiring the `s` value to be in the lower
         * half order, and the `v` value to be either 27 or 28.
         *
         * IMPORTANT: `hash` _must_ be the result of a hash operation for the
         * verification to be secure: it is possible to craft signatures that
         * recover to arbitrary addresses for non-hashed data. A safe way to ensure
         * this is by receiving a hash of the original message (which may otherwise
         * be too long), and then calling {toEthSignedMessageHash} on it.
         *
         * Documentation for signature generation:
         * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
         * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
         *
         * _Available since v4.3._
         */
        function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
            // Check the signature length
            // - case 65: r,s,v signature (standard)
            // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
            if (signature.length == 65) {
                bytes32 r;
                bytes32 s;
                uint8 v;
                // ecrecover takes the signature parameters, and the only way to get them
                // currently is to use assembly.
                assembly {
                    r := mload(add(signature, 0x20))
                    s := mload(add(signature, 0x40))
                    v := byte(0, mload(add(signature, 0x60)))
                }
                return tryRecover(hash, v, r, s);
            } else if (signature.length == 64) {
                bytes32 r;
                bytes32 vs;
                // ecrecover takes the signature parameters, and the only way to get them
                // currently is to use assembly.
                assembly {
                    r := mload(add(signature, 0x20))
                    vs := mload(add(signature, 0x40))
                }
                return tryRecover(hash, r, vs);
            } else {
                return (address(0), RecoverError.InvalidSignatureLength);
            }
        }
        /**
         * @dev Returns the address that signed a hashed message (`hash`) with
         * `signature`. This address can then be used for verification purposes.
         *
         * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
         * this function rejects them by requiring the `s` value to be in the lower
         * half order, and the `v` value to be either 27 or 28.
         *
         * IMPORTANT: `hash` _must_ be the result of a hash operation for the
         * verification to be secure: it is possible to craft signatures that
         * recover to arbitrary addresses for non-hashed data. A safe way to ensure
         * this is by receiving a hash of the original message (which may otherwise
         * be too long), and then calling {toEthSignedMessageHash} on it.
         */
        function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
            (address recovered, RecoverError error) = tryRecover(hash, signature);
            _throwError(error);
            return recovered;
        }
        /**
         * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
         *
         * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
         *
         * _Available since v4.3._
         */
        function tryRecover(
            bytes32 hash,
            bytes32 r,
            bytes32 vs
        ) internal pure returns (address, RecoverError) {
            bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
            uint8 v = uint8((uint256(vs) >> 255) + 27);
            return tryRecover(hash, v, r, s);
        }
        /**
         * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
         *
         * _Available since v4.2._
         */
        function recover(
            bytes32 hash,
            bytes32 r,
            bytes32 vs
        ) internal pure returns (address) {
            (address recovered, RecoverError error) = tryRecover(hash, r, vs);
            _throwError(error);
            return recovered;
        }
        /**
         * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
         * `r` and `s` signature fields separately.
         *
         * _Available since v4.3._
         */
        function tryRecover(
            bytes32 hash,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) internal pure returns (address, RecoverError) {
            // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
            // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
            // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
            // signatures from current libraries generate a unique signature with an s-value in the lower half order.
            //
            // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
            // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
            // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
            // these malleable signatures as well.
            if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
                return (address(0), RecoverError.InvalidSignatureS);
            }
            if (v != 27 && v != 28) {
                return (address(0), RecoverError.InvalidSignatureV);
            }
            // If the signature is valid (and not malleable), return the signer address
            address signer = ecrecover(hash, v, r, s);
            if (signer == address(0)) {
                return (address(0), RecoverError.InvalidSignature);
            }
            return (signer, RecoverError.NoError);
        }
        /**
         * @dev Overload of {ECDSA-recover} that receives the `v`,
         * `r` and `s` signature fields separately.
         */
        function recover(
            bytes32 hash,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) internal pure returns (address) {
            (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
            _throwError(error);
            return recovered;
        }
        /**
         * @dev Returns an Ethereum Signed Message, created from a `hash`. This
         * produces hash corresponding to the one signed with the
         * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
         * JSON-RPC method as part of EIP-191.
         *
         * See {recover}.
         */
        function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
            // 32 is the length in bytes of hash,
            // enforced by the type signature above
            return keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
    32", hash));
        }
        /**
         * @dev Returns an Ethereum Signed Message, created from `s`. This
         * produces hash corresponding to the one signed with the
         * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
         * JSON-RPC method as part of EIP-191.
         *
         * See {recover}.
         */
        function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
            return keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
    ", Strings.toString(s.length), s));
        }
        /**
         * @dev Returns an Ethereum Signed Typed Data, created from a
         * `domainSeparator` and a `structHash`. This produces hash corresponding
         * to the one signed with the
         * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
         * JSON-RPC method as part of EIP-712.
         *
         * See {recover}.
         */
        function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
            return keccak256(abi.encodePacked("\\x19\\x01", domainSeparator, structHash));
        }
    }
    // SPDX-License-Identifier: MIT
    // OpenZeppelin Contracts v4.4.1 (utils/Strings.sol)
    pragma solidity ^0.8.0;
    /**
     * @dev String operations.
     */
    library Strings {
        bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
        /**
         * @dev Converts a `uint256` to its ASCII `string` decimal representation.
         */
        function toString(uint256 value) internal pure returns (string memory) {
            // Inspired by OraclizeAPI's implementation - MIT licence
            // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol
            if (value == 0) {
                return "0";
            }
            uint256 temp = value;
            uint256 digits;
            while (temp != 0) {
                digits++;
                temp /= 10;
            }
            bytes memory buffer = new bytes(digits);
            while (value != 0) {
                digits -= 1;
                buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
                value /= 10;
            }
            return string(buffer);
        }
        /**
         * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
         */
        function toHexString(uint256 value) internal pure returns (string memory) {
            if (value == 0) {
                return "0x00";
            }
            uint256 temp = value;
            uint256 length = 0;
            while (temp != 0) {
                length++;
                temp >>= 8;
            }
            return toHexString(value, length);
        }
        /**
         * @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] = _HEX_SYMBOLS[value & 0xf];
                value >>= 4;
            }
            require(value == 0, "Strings: hex length insufficient");
            return string(buffer);
        }
    }
    // 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 (last updated v4.5.0) (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 functionCall(target, data, "Address: low-level call failed");
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
         * `errorMessage` as a fallback revert reason when `target` reverts.
         *
         * _Available since v3.1._
         */
        function functionCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal returns (bytes memory) {
            return functionCallWithValue(target, data, 0, errorMessage);
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
         * but also transferring `value` wei to `target`.
         *
         * Requirements:
         *
         * - the calling contract must have an ETH balance of at least `value`.
         * - the called Solidity function must be `payable`.
         *
         * _Available since v3.1._
         */
        function functionCallWithValue(
            address target,
            bytes memory data,
            uint256 value
        ) internal returns (bytes memory) {
            return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
        }
        /**
         * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
         * with `errorMessage` as a fallback revert reason when `target` reverts.
         *
         * _Available since v3.1._
         */
        function functionCallWithValue(
            address target,
            bytes memory data,
            uint256 value,
            string memory errorMessage
        ) internal returns (bytes memory) {
            require(address(this).balance >= value, "Address: insufficient balance for call");
            require(isContract(target), "Address: call to non-contract");
            (bool success, bytes memory returndata) = target.call{value: value}(data);
            return verifyCallResult(success, returndata, errorMessage);
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
         * but performing a static call.
         *
         * _Available since v3.3._
         */
        function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
            return functionStaticCall(target, data, "Address: low-level static call failed");
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
         * but performing a static call.
         *
         * _Available since v3.3._
         */
        function functionStaticCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal view returns (bytes memory) {
            require(isContract(target), "Address: static call to non-contract");
            (bool success, bytes memory returndata) = target.staticcall(data);
            return verifyCallResult(success, returndata, errorMessage);
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
         * but performing a delegate call.
         *
         * _Available since v3.4._
         */
        function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
            return functionDelegateCall(target, data, "Address: low-level delegate call failed");
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
         * but performing a delegate call.
         *
         * _Available since v3.4._
         */
        function functionDelegateCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal returns (bytes memory) {
            require(isContract(target), "Address: delegate call to non-contract");
            (bool success, bytes memory returndata) = target.delegatecall(data);
            return verifyCallResult(success, returndata, errorMessage);
        }
        /**
         * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
         * revert reason using the provided one.
         *
         * _Available since v4.3._
         */
        function verifyCallResult(
            bool success,
            bytes memory returndata,
            string memory errorMessage
        ) internal pure returns (bytes memory) {
            if (success) {
                return returndata;
            } else {
                // Look for revert reason and bubble it up if present
                if (returndata.length > 0) {
                    // The easiest way to bubble the revert reason is using memory via assembly
                    assembly {
                        let returndata_size := mload(returndata)
                        revert(add(32, returndata), returndata_size)
                    }
                } else {
                    revert(errorMessage);
                }
            }
        }
    }
    // 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 v4.5.0) (token/ERC721/extensions/IERC721Enumerable.sol)
    pragma solidity ^0.8.0;
    import "../IERC721.sol";
    /**
     * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
     * @dev See https://eips.ethereum.org/EIPS/eip-721
     */
    interface IERC721Enumerable is IERC721 {
        /**
         * @dev Returns the total amount of tokens stored by the contract.
         */
        function totalSupply() external view returns (uint256);
        /**
         * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
         * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
         */
        function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256);
        /**
         * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
         * Use along with {totalSupply} to enumerate all tokens.
         */
        function tokenByIndex(uint256 index) external view returns (uint256);
    }
    // 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 v4.6.0) (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 be have been allowed to move this token by either {approve} or {setApprovalForAll}.
         * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
         *
         * Emits a {Transfer} event.
         */
        function safeTransferFrom(
            address from,
            address to,
            uint256 tokenId
        ) external;
        /**
         * @dev Transfers `tokenId` token from `from` to `to`.
         *
         * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
         *
         * Requirements:
         *
         * - `from` cannot be the zero address.
         * - `to` cannot be the zero address.
         * - `tokenId` token must be owned by `from`.
         * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
         *
         * Emits a {Transfer} event.
         */
        function transferFrom(
            address from,
            address to,
            uint256 tokenId
        ) external;
        /**
         * @dev Gives permission to `to` to transfer `tokenId` token to another account.
         * The approval is cleared when the token is transferred.
         *
         * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
         *
         * Requirements:
         *
         * - The caller must own the token or be an approved operator.
         * - `tokenId` must exist.
         *
         * Emits an {Approval} event.
         */
        function approve(address to, uint256 tokenId) external;
        /**
         * @dev 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 v4.4.1 (token/ERC1155/IERC1155.sol)
    pragma solidity ^0.8.0;
    import "../../utils/introspection/IERC165.sol";
    /**
     * @dev Required interface of an ERC1155 compliant contract, as defined in the
     * https://eips.ethereum.org/EIPS/eip-1155[EIP].
     *
     * _Available since v3.1._
     */
    interface IERC1155 is IERC165 {
        /**
         * @dev Emitted when `value` tokens of token type `id` are transferred from `from` to `to` by `operator`.
         */
        event TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value);
        /**
         * @dev Equivalent to multiple {TransferSingle} events, where `operator`, `from` and `to` are the same for all
         * transfers.
         */
        event TransferBatch(
            address indexed operator,
            address indexed from,
            address indexed to,
            uint256[] ids,
            uint256[] values
        );
        /**
         * @dev Emitted when `account` grants or revokes permission to `operator` to transfer their tokens, according to
         * `approved`.
         */
        event ApprovalForAll(address indexed account, address indexed operator, bool approved);
        /**
         * @dev Emitted when the URI for token type `id` changes to `value`, if it is a non-programmatic URI.
         *
         * If an {URI} event was emitted for `id`, the standard
         * https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[guarantees] that `value` will equal the value
         * returned by {IERC1155MetadataURI-uri}.
         */
        event URI(string value, uint256 indexed id);
        /**
         * @dev Returns the amount of tokens of token type `id` owned by `account`.
         *
         * Requirements:
         *
         * - `account` cannot be the zero address.
         */
        function balanceOf(address account, uint256 id) external view returns (uint256);
        /**
         * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {balanceOf}.
         *
         * Requirements:
         *
         * - `accounts` and `ids` must have the same length.
         */
        function balanceOfBatch(address[] calldata accounts, uint256[] calldata ids)
            external
            view
            returns (uint256[] memory);
        /**
         * @dev Grants or revokes permission to `operator` to transfer the caller's tokens, according to `approved`,
         *
         * Emits an {ApprovalForAll} event.
         *
         * Requirements:
         *
         * - `operator` cannot be the caller.
         */
        function setApprovalForAll(address operator, bool approved) external;
        /**
         * @dev Returns true if `operator` is approved to transfer ``account``'s tokens.
         *
         * See {setApprovalForAll}.
         */
        function isApprovedForAll(address account, address operator) external view returns (bool);
        /**
         * @dev Transfers `amount` tokens of token type `id` from `from` to `to`.
         *
         * Emits a {TransferSingle} event.
         *
         * Requirements:
         *
         * - `to` cannot be the zero address.
         * - If the caller is not `from`, it must be have been approved to spend ``from``'s tokens via {setApprovalForAll}.
         * - `from` must have a balance of tokens of type `id` of at least `amount`.
         * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
         * acceptance magic value.
         */
        function safeTransferFrom(
            address from,
            address to,
            uint256 id,
            uint256 amount,
            bytes calldata data
        ) external;
        /**
         * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {safeTransferFrom}.
         *
         * Emits a {TransferBatch} event.
         *
         * Requirements:
         *
         * - `ids` and `amounts` must have the same length.
         * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
         * acceptance magic value.
         */
        function safeBatchTransferFrom(
            address from,
            address to,
            uint256[] calldata ids,
            uint256[] calldata amounts,
            bytes calldata data
        ) external;
    }
    // SPDX-License-Identifier: MIT
    // OpenZeppelin Contracts (last updated v4.6.0) (interfaces/IERC2981.sol)
    pragma solidity ^0.8.0;
    import "../utils/introspection/IERC165.sol";
    /**
     * @dev Interface for the NFT Royalty Standard.
     *
     * A standardized way to retrieve royalty payment information for non-fungible tokens (NFTs) to enable universal
     * support for royalty payments across all NFT marketplaces and ecosystem participants.
     *
     * _Available since v4.5._
     */
    interface IERC2981 is IERC165 {
        /**
         * @dev Returns how much royalty is owed and to whom, based on a sale price that may be denominated in any unit of
         * exchange. The royalty amount is denominated and should be paid in that same unit of exchange.
         */
        function royaltyInfo(uint256 tokenId, uint256 salePrice)
            external
            view
            returns (address receiver, uint256 royaltyAmount);
    }
    // SPDX-License-Identifier: MIT
    // OpenZeppelin Contracts v4.4.1 (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 Returns the address of the current owner.
         */
        function owner() public view virtual returns (address) {
            return _owner;
        }
        /**
         * @dev Throws if called by any account other than the owner.
         */
        modifier onlyOwner() {
            require(owner() == _msgSender(), "Ownable: caller is not the owner");
            _;
        }
        /**
         * @dev Leaves the contract without owner. It will not be possible to call
         * `onlyOwner` functions anymore. Can only be called by the current owner.
         *
         * NOTE: Renouncing ownership will leave the contract without an owner,
         * thereby removing any functionality that is only available to the owner.
         */
        function renounceOwnership() public virtual onlyOwner {
            _transferOwnership(address(0));
        }
        /**
         * @dev Transfers ownership of the contract to a new account (`newOwner`).
         * Can only be called by the current owner.
         */
        function transferOwnership(address newOwner) public virtual onlyOwner {
            require(newOwner != address(0), "Ownable: new owner is the zero address");
            _transferOwnership(newOwner);
        }
        /**
         * @dev Transfers ownership of the contract to a new account (`newOwner`).
         * Internal function without access restriction.
         */
        function _transferOwnership(address newOwner) internal virtual {
            address oldOwner = _owner;
            _owner = newOwner;
            emit OwnershipTransferred(oldOwner, newOwner);
        }
    }