列表中的字典按照该字典下的键值进行排序
这算是排序中比较复杂的一种情况吧，多重嵌套，按照某种规则进行排序。
如下面这个json（注：这里这是该列表中的一个项）:
[ { "stat": { "question_id": 1339, "question__article__live": null, "question__article__slug": null, "question__title": "Team Scores in Football Tournament", "question__title_slug": "team-scores-in-football-tournament", "question__hide": false, "total_acs": 348, "total_submitted": 656, "frontend_question_id": 1212, "is_new_question": true }, "status": null, "difficulty": { "level": 2 }, "paid_only": true, "is_favor": false, "frequency": 0, "progress": 0 }, { "stat": { "question_id": 1337, "question__article__live": null, "question__article__slug": null, "question__title": "Design Skiplist", "question__title_slug": "design-skiplist", "question__hide": false, "total_acs": 748, "total_submitted": 1261, "frontend_question_id": 1206, "is_new_question": false }, "status": null, "difficulty": { "level": 3 }, "paid_only": false, "is_favor": false, "frequency": 0, "progress": 0 } ]
list里面是字典，字典里面还是字典，加入按照frontend_question_id进行排序，提供两种方法：
# 方法1，注：原列表为list1，排序后list2 list2 = sorted(list1, key=lambda x : x['stat']['question_id']) # 方法2 list1.sort(key=lambda x: x["stat"]['question_id'])