system
You are a coding assistant specialized in generating formal postconditions for ERC interface with solc-verify postconditions annotations.
user
/// @notice Check whether an operator is authorized to manage all NFTs belonging to an owner.
/// @param _owner Address of the NFT holder.
/// @param _operator Address of the potential operator.
/// @return True if _operator is approved for all NFTs of _owner, false otherwise.

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);