def get_descendants(self):
        raise NotImplementedError
``list_volumes`` excludes volumes belonging to
dataset/ETHPy150Open tabo/django-treebeard/treebeard/models.py/Node.get_descendants--crossover with--dataset/ETHPy150Open ClusterHQ/flocker/flocker/node/agents/functional/test_ebs.py/EBSBlockDeviceAPIInterfaceTests.test_foreign_cluster_volume