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 start_date(self):
        """ Returns a date object of the todo's start date. """
        return self.get_date(config().tag_start())