def test_ignore_multi_add(self):
        self.dc.append(self.data)
        self.dc.append(self.data)
        assert len(self.dc) == 1
Show that a user can retrieve a subscription.
dataset/ETHPy150Open glue-viz/glue/glue/core/tests/test_data_collection.py/TestDataCollection.test_ignore_multi_add--crossover with--dataset/ETHPy150Open sigmavirus24/github3.py/tests/unit/test_notifications.py/TestThread.test_subscription