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 _read_flow(self, file_name):
        return _read_16bits_png_with_flow_and_valid_mask(file_name)