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 _get(delta, start):
            p = start
            while delta:
                p = p.next
                delta -= 1
            return p.val