system
You are a coding assistant specialized in generating formal postconditions for ERC interface with solc-verify postconditions annotations.
user
/// @notice Determine whether _operator has been approved to handle all NFTs for _owner.
/// @param _owner The address that owns the NFTs in question.
/// @param _operator The address to be checked for operator rights.
/// @return True if _operator is an approved operator, otherwise false.

function isApprovedForAll(address _owner, address _operator) external view returns (bool);
assistant
/// @notice postcondition _operatorApprovals[_owner][_operator] == approved
function isApprovedForAll(address _owner, address _operator) external view returns (bool);