code: def followers(self):
          
          from .author import Author, ANONYMOUS
          self._make_soup()
          gotten_data_num = 20
          data = {
              '_xsrf': self.xsrf,
              'start': '',
              'offset': 0
          }
          while gotten_data_num == 20:
              res = self._session.post(
                  Topic_Get_More_Follower_Url.format(self.id), data=data)
              j = res.json()['msg']
              gotten_data_num = j[0]
              data['offset'] += gotten_data_num
              soup = BeautifulSoup(j[1])
              divs = soup.find_all('div', class_='zm-person-item')
              for div in divs:
                  h2 = div.h2
                  url = Zhihu_URL + h2.a['href']
                  name = h2.a.text
                  motto = h2.parent.div.text.strip()
                  try:
                      yield Author(url, name, motto, session=self._session)
                  except ValueError:  # invalid url
                      yield ANONYMOUS
              data['start'] = int(re_get_number.match(divs[-1]['id']).group(1))
docs: 获取话题关注者
  
          :return: 话题关注者，返回生成器
          :rtype: Author.Iterable