def test_sentinel_is_self(self):
        self.assertIs(self.sentinel_a, self.sentinel_a)
        self.assertIs(self.sentinel_b, self.sentinel_b)
``datasets_from_deployment`` may return multiple primary datasets.
dataset/ETHPy150Open duerrp/pyexperiment/tests/test_sentinel.py/TestSentinel.test_sentinel_is_self--crossover with--dataset/ETHPy150Open ClusterHQ/flocker/flocker/control/test/test_httpapi.py/DatasetsFromDeploymentTests.test_multiple_primary_manifestations