def test_order(self):
        assert (event.Priority.PRE_CORE
                > event.Priority.CORE
                > event.Priority.POST_CORE
                > event.Priority.PRE_DEFAULT
                > event.Priority.DEFAULT
                > event.Priority.POST_DEFAULT)
def combinationSum(self, candidates, target):
        candidates.sort()
        self.result = []
        self.dfs(candidates,target,0,[])
        return self.result