def test_bool(self):
        prio_set_list = event._PrioritizedSetList()

        assert bool(prio_set_list) is False

        prio_set_list.add(0, None)
        assert bool(prio_set_list) is True
def setdefault(self, key, default=None):
        return self._collection.setdefault(key, self._from_python(key, default))