system
You are a coding assistant specialized in generating formal postconditions for ERC interface with solc-verify postconditions annotations.
user
/// @notice Authorize an address to manage a specific NFT.
/// @dev The zero address removes any existing approval for the NFT.
/// This action is restricted to the NFT owner or their authorized operator.
/// @param _approved Address to be approved for managing the NFT.
/// @param _tokenId Unique identifier of the NFT to approve.

function approve(address _approved, uint256 _tokenId) external payable;
assistant
/// @notice postcondition _tokenApprovals[_tokenId] == _approved
function approve(address _approved, uint256 _tokenId) external;