code: def top_authors(self):
          
          from .author import Author, ANONYMOUS
          self._make_soup()
          t = self.soup.find('div', id='zh-topic-top-answerer')
          if t is None:
              return
          for d in t.find_all('div', class_='zm-topic-side-person-item-content'):
              url = Zhihu_URL + d.a['href']
              name = d.a.text
              motto = d.find('span', class_='bio')['title']
              try:
                  yield Author(url, name, motto, session=self._session)
              except ValueError:  # invalid url
                  yield ANONYMOUS
docs: 获取最佳回答者
  
          :return: 此话题下最佳回答者，一般来说是5个，要不就没有，返回生成器
          :rtype: Author.Iterable