你好，这个爬虫脚本失效了。

[daiwc]

Traceback (most recent call last):
File "zhihu_spider.py", line 90, in
zh_download(question_id='1072019411')
File "zhihu_spider.py", line 66, in zh_download
zhihu_spider(question_id)
File "zhihu_spider.py", line 36, in zhihu_spider
for answer in answers:
TypeError: 'NoneType' object is not iterable