def onepage(url):
   r = requests.get(url)
   r.encoding = "utf-8"
   html = r.text

   soup = BeautifulSoup(html, "html.parser")
   comments_sec = soup.find("div", "mod-bd")
   comments_list = comments_sec.find_all("p", "")
   lst = []   
   for i in range(len(comments_list)):
     lst.append(comments_list[i].text.strip())   
   return lst


def parsepage(movie_id, page_num):
    data = []
    for i in range(page_num):
          url = "https://movie.douban.com/subject/"+ str(movie_id) + "/comments?start=" + str(20 * i) + "&limit=20"
          data += onepage(url)
          print("parsing page %d" % (i+1))
          time.sleep(3)#
    return " ".join(data)

程序如上 为什么最后的data显示没有被定义呢