contract ERC721 {
    // Required methods 

    function ownerOf(uint32 _tokenId) public view returns (address owner);
    function approve(address _to, uint32 _tokenId) public returns (bool success);
    function transfer(address _to, uint32 _tokenId) public;
    function transferFrom(address _from, address _to, uint32 _tokenId) public returns (bool);
    function totalSupply() public view returns (uint total);
    function balanceOf(address _owner) public view returns (uint balance);

}
/// @title Interface for contracts conforming to ERC-721: Non-Fungible Tokens
/// @author Dieter Shirley <dete@axiomzen.co> (https://github.com/dete)
function ownerOf(uint32 _tokenId) public view returns (address owner);
// Required methods 