@abc.abstractmethod
    def __call__(self, target, cred, enforcer):

        pass
@return bool: True only if all messages in the task tree have been
dataset/ETHPy150Open CiscoSystems/avos/openstack_dashboard/openstack/common/policy.py/BaseCheck.__call__--crossover with--dataset/ETHPy150Open ClusterHQ/eliot/eliot/_parse.py/Task.is_complete