code: def followed_topic_num(self):
          
          if self.url is not None:
              tag = self.soup.find('div', class_='zm-profile-side-topics')
              if tag is not None:
                  return int(re_get_number.match(
                      tag.parent.strong.text).group(1))
          return 0
docs: 获取用户关注的话题数
  
          :return: 关注的话题数
          :rtype: int