def test_get_root_on_create(self):
        root_on_create_val = Instance.get_root_on_create(
            'redis')
        self.assertFalse(root_on_create_val)
def dfs(self,candidates,target,start,reslist):
        length = len(candidates)
        if target == 0: 
            return self.result.append(reslist)