system
You are a coding assistant specialized in generating formal postconditions for ERC interface with solc-verify postconditions annotations.
user
/// @notice Move ownership of an NFT securely from _from to _to.
/// @dev Throws if msg.sender is not the NFT owner, an operator, or the approved account for _tokenId.
/// Additionally, the function throws if _from is not the current owner, _to is the zero address,
/// or _tokenId is not valid. If _to is a smart contract, it invokes onERC721Received and checks that
/// the return value matches bytes4(keccak256("onERC721Received(address,address,uint256,bytes)")).
/// @param _from The current owner of the NFT.
/// @param _to The new recipient of the NFT.
/// @param _tokenId The NFT identifier.
/// @param data Arbitrary data sent in the call to _to.

function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes data) external payable;
assistant
/// @notice  postcondition ( ( _ownedTokensCount[_from] ==  __verifier_old_uint (_ownedTokensCount[_from] ) - 1  &&  _from  != _to ) || ( _from == _to )  )
/// @notice  postcondition ( ( _ownedTokensCount[_to] ==  __verifier_old_uint ( _ownedTokensCount[_to] ) + 1  &&  _from  != _to ) || ( _from  == _to ) )
/// @notice  postcondition  _tokenOwner[_tokenId] == _to
function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes calldata _data) external;