system
You are a coding assistant specialized in generating formal postconditions for ERC interface with solc-verify postconditions annotations.
user
/// @notice Retrieve the address approved to manage a specific NFT.
/// @dev Reverts if _tokenId does not represent a valid NFT.
/// @param _tokenId The identifier of the NFT for which to get the approved address.
/// @return The address approved for this NFT, or the zero address if none 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);