def test_contains(self):
        prio_set_list = event._PrioritizedSetList()
        obj = object()

        prio_set_list.add(0, obj)
        assert obj in prio_set_list
def _update_height(self, height_diff):
    if self._items_total_height is None:
      self._items_total_height = self.get_allocation().height