@property
    def is_sleeping(self):
        return self._state == self.STATE_SLEEPING
Ensures that each node's parent is cached by ``cache_tree_children``.
dataset/ETHPy150Open gmr/helper/helper/controller.py/Controller.is_sleeping--crossover with--dataset/ETHPy150Open django-mptt/django-mptt/tests/myapp/tests.py/CacheTreeChildrenTestCase.test_cache_tree_children_caches_parents