contract ERC721 {
    // Required Functions
    function implementsERC721() public pure returns (bool);
    function totalSupply() public view returns (uint256);
    function balanceOf(address _owner) public view returns (uint256);
    function ownerOf(uint256 _tokenId) public view returns (address);
    function transfer(address _to, uint _tokenId) public;
    function approve(address _to, uint256 _tokenId) public;
    function transferFrom(address _from, address _to, uint256 _tokenId) public;

    // Optional Functions
    function name() public pure returns (string);
    function symbol() public pure returns (string);

    // Required Events
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
}
function name() public pure returns (string);

// Optional Functions