code: def hot_questions(self):
          
          from .question import Question
          hot_questions_url = Topic_Hot_Questions_Url.format(self.id)
          params = {'start': 0, '_xsrf': self.xsrf}
          res = self._session.get(hot_questions_url)
          soup = BeautifulSoup(res.content)
          while True:
              questions_duplicate = soup.find_all('a', class_='question_link')
              # 如果话题下无问题，则直接返回
              if len(questions_duplicate) == 0:
                  return
                  # 去除重复的问题
              questions = list(set(questions_duplicate))
              questions.sort(key=self._get_score, reverse=True)
              last_score = soup.find_all(
                  'div', class_='feed-item')[-1]['data-score']
              for q in questions:
                  question_url = Zhihu_URL + q['href']
                  question_title = q.text.strip()
                  question = Question(question_url, question_title,
                                      session=self._session)
                  yield question
              params['offset'] = last_score
              res = self._session.post(hot_questions_url, data=params)
              gotten_feed_num = res.json()['msg'][0]
              # 如果得到问题数量为0则返回
              if gotten_feed_num == 0:
                  return
              soup = BeautifulSoup(res.json()['msg'][1])
docs: 获取话题下热门的问题
  
          :return: 话题下的热门动态中的问题，按热门度顺序返回生成器
          :rtype: Question.Iterable