def keys(self):
        return [key for key, value in self.iteritems()]
Check that the nested collector doesn't query for DO_NOTHING objects.
dataset/ETHPy150Open openstack/oslo.db/oslo_db/sqlalchemy/models.py/ModelBase.keys--crossover with--dataset/ETHPy150Open pydanny/django-admin2/example/blog/tests/test_nestedobjects.py/NestedObjectsTests.test_on_delete_do_nothing