def test_lookup(self):
        assert event.Priority.lookup(event.Priority.CORE) is event.Priority.CORE
        assert event.Priority.lookup(event.Priority.CORE.value) is event.Priority.CORE
        assert event.Priority.lookup(-12312412) == -12312412
def dfs(self,candidates,target,start,reslist):
        length = len(candidates)
        if target == 0: 
            return self.result.append(reslist)