Django的URL是如何写的？

urls.py
----
from django.conf.urls.defaults import *
urlpatterns = patterns('qcx.blog.views',
(r'^now/$', current_datetime),#以“now/”开头，后面不要任何字符时
(r'^now/plus(\d{1,2})hours/$', hours_ahead),#“plus”为常量字符，(\d{1,2}) 数字1-2位
(r'^now/minus(\d{1,2})hours/$', hours_behind),
(r'^now/in_chicago/$', now_in_chicago),
(r'^now/in_london/$', now_in_london),
)