    function transferFrom(
        address _from,
        address _to,
        uint256 _tokenId,
        bytes calldata /* _data */
    ) external payable {
        // checks that the user is authorised
        _transfer(_from, _to, _tokenId);
    }

    /// @inheritdoc IERC721Metadata
    function transferFrom(
        address _from,
        address _to,
        uint256 _tokenId
    ) external payable {
        // checks that the user is authorised
        _transfer(_from, _to, _tokenId);
    }

    /// @inheritdoc IERC721Metadata
    function safeTransferFrom(
        address _from,
        address _to,
        uint256 _tokenId
    ) external payable {
        _transfer(_from, _to, _tokenId);
        _onTransferReceived(msg.sender, _from, _to, _tokenId);
    }

    /// @inheritdoc IERC721Metadata
    function safeTransferFrom(
        address _from,
        address _to,
        uint256 _tokenId,
        bytes calldata /* _data */
    ) external payable {
        _transfer(_from, _to, _tokenId);
        _onTransferReceived(msg.sender, _from, _to, _tokenId);
    }

    /// @inheritdoc IERC721Metadata
    function approve(address _approved, uint256 _tokenId) external payable {
        _requireAuthorised(msg.sender, _tokenId);
        getApproved[_tokenId] = _approved;
    }
