contract ERC721 {
    function totalSupply() public view returns (uint256 total);
    function balanceOf(address _owner) public view returns (uint256 balance);
    function ownerOf(uint256 _tokenId) external view   returns (address owner);
    // ownerof
    // deploy:  public ->external
    // test : external -> public
    function approve(address _to, uint256 _tokenId) external;
    function transfer(address _to, uint256 _tokenId) external;
    function transferFrom(address _from, address _to, uint256 _tokenId) external;

    event Transfer(address from, address to, uint256 tokenId);
    event Approval(address owner, address approved, uint256 tokenId);

    function supportsInterface(bytes4 _interfaceID) external view returns (bool);

}
function approve(address _to, uint256 _tokenId) external;

// ownerof
// deploy:  public ->external
// test : external -> public