def comment_num(self):
        """
        :return: 答案下评论的数量
        :rtype: int
        """
        comment = self.soup.select_one("div.answer-actions a.toggle-comment")
        comment_num_string = comment.text
        number = comment_num_string.split()[0]
        return int(number) if number.isdigit() else 0
:return: 答案下评论的数量
        :rtype: int