老师你好，对着你的代码，我编译出现这个，我的是3.6版本
Traceback (most recent call last):
File "D:\Python\spider_main.py", line 33, in <module>
obj_spider.craw(root_url)
File "D:\Python\spider_main.py", line 13, in craw
self.urls.add_new_url(root_url)
TypeError: add_new_url() takes 1 positional argument but 2 were given
