def test_add_already_added(self):
        prio_set_list = event._PrioritizedSetList()
        obj = object()
        prio_set_list.add(0, obj)

        with pytest.raises(ValueError) as excinfo:
            prio_set_list.add(0, obj)
        excinfo.match(r"has already been added")

        with pytest.raises(ValueError) as excinfo:
            prio_set_list.add(1, obj)
        excinfo.match(r"has already been added")
def commit(self):
        context = self.pop()
        if self:
            # savepoint
            self[-1]['cbs'].extend(context['cbs'])
            self[-1]['dirty'] = self[-1]['dirty'] or context['dirty']
        else:
            # transaction
            for func, args, kwargs in context['cbs']:
                func(*args, **kwargs)