old_contents: from django.conf.urls import patterns, url
  from cab.views import popular, snippets
  
  urlpatterns = patterns('',
      url(r'^$',
          popular.top_authors,
          name='cab_top_authors'),
      url(r'^(?P<username>[-\w]+)/$',
          snippets.author_snippets,
          name='cab_author_snippets'),
  )
  
new_contents: from django.conf.urls import patterns, url
  from cab.views import popular, snippets
  
  urlpatterns = patterns('',
      url(r'^$',
          popular.top_authors,
          name='cab_top_authors'),
      url(r'^(?P<username>[\w.@+-]+)/$',
          snippets.author_snippets,
          name='cab_author_snippets'),
  )
  
subject: Use better username pattern.