old_contents: from django.conf.urls import include, url
  from . import views
  
  urlpatterns = [
      url(r'^$',  views.about, name='about'),
      url(r'^home/$',  views.home, name='homet'),
      url(r'^create_room/$', views.create_room, name='create_room'),
      url(r'^join_room/$', views.join_room, name='join_room'),
      url(r'^(?P<label>[\w-]{,50})/$', views.chat_room, name='chat_room'),
  ]
  
new_contents: from django.conf.urls import include, url
  from . import views
  
  urlpatterns = [
      url(r'^$',  views.about, name='about'),
      url(r'^home/$',  views.home, name='home'),
      url(r'^create_room/$', views.create_room, name='create_room'),
      url(r'^join_room/$', views.join_room, name='join_room'),
      url(r'^(?P<label>[\w-]{,50})/$', views.chat_room, name='chat_room'),
  ]
  
subject: update error page