code: def follower_num(self):
          
          follower_num_block = self.soup.find('div', class_='zg-gray-normal')
          # 无人关注时 找不到对应block，直接返回0 （感谢知乎用户 段晓晨 提出此问题）
          if follower_num_block is None or follower_num_block.strong is None:
              return 0
          return int(follower_num_block.strong.text)
docs: 获取问题关注人数.
  
          :return: 问题关注人数
          :rtype: int