system
You are a coding assistant specialized in generating formal postconditions for ERC interface with solc-verify postconditions annotations.
user
/// @notice Transfer ownership of an NFT -- THE CALLER IS RESPONSIBLE
///  TO CONFIRM THAT `_to` IS CAPABLE OF RECEIVING NFTS OR ELSE
///  THEY MAY BE PERMANENTLY LOST
/// @dev Throws unless `msg.sender` is the current owner, an authorized
///  operator, or the approved address for this NFT. Throws if `_from` is
///  not the current owner. Throws if `_to` is the zero address. Throws if
///  `_tokenId` is not a valid NFT.
/// @param _from The current owner of the NFT
/// @param _to The new owner
/// @param _tokenId The NFT to transfer

function transferFrom(address _from, address _to, uint256 _tokenId) external payable;
assistant
/// @notice  postcondition ( ( _ownedTokensCount[_from] ==  __verifier_old_uint (_ownedTokensCount[_from] ) - 1  &&  _from  != _to ) || ( _from == _to )  )
/// @notice  postcondition ( ( _ownedTokensCount[_to] ==  __verifier_old_uint ( _owned_kensCount[to] ) + 1  &&  _from  != _to ) || ( _from  == _to ) )
/// @notice  postcondition  _tokenOwner[_tokenId] == _to
function transferFrom(address _from, address _to, uint256 _tokenId) external;