照著老師的代碼打的，new_urls也定義了，還是報(bào)錯(cuò)，求大神指點(diǎn)
Traceback (most recent call last):
? File "E:\java\imooc\baike_spider\spider_main.py", line 38, in <module>
? ? obj_spider.craw(root_url)?
? File "E:\java\imooc\baike_spider\spider_main.py", line 13, in craw
? ? self.urls.add_new_url(root_url)
? File "E:\java\imooc\baike_spider\url_manager.py", line 10, in add_new_url
? ? if url not in self.new_urls and url not in self.old_urls:
AttributeError: 'UrlManager' object has no attribute 'new_urls'
