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 add_target_handle(self, layer):
        input_handle = layer.register_forward_hook(get_target_input)
        self.target_handle = input_handle