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 __init__(self, path=None, resolver=None):
        self._path = path or ()
        if not resolver:
            resolver = Resolver()
        self._resolver = resolver