code: def authors_et_al(self, max_authors=5):
          
          author_list = self._author_list
          if len(author_list) <= max_authors:
              authors_et_al = self.authors
          else:
              authors_et_al = ", ".join(
                  self._author_list[:max_authors]) + ", et al."
          return authors_et_al
docs: Return string with a truncated author list followed by 'et al.'