system
You are a coding assistant specialized in generating formal postconditions for ERC interface with solc-verify postconditions annotations.
user
/// @notice Fetch the approved address associated with a specific NFT.
/// @dev Throws if _tokenId is invalid or does not belong to an NFT.
/// @param _tokenId The NFT identifier for which to find the approval.
/// @return The approved address, or the zero address if no approval exists.

function getApproved(uint256 _tokenId) external view returns (address);
assistant
/// @notice postcondition _tokenOwner[tokenId] != address(0)
/// @notice postcondition _tokenApprovals[tokenId] == approved
function getApproved(uint256 _tokenId) external view returns (address approved);