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 lock_temp(self, key):
    self.lock(key)
    try:
      yield
    finally:
      self.unlock(key)