old_contents: from django.conf.urls import url
  from docs.views import *
  
  urlpatterns = [
      url(r'^(\d+)/$', DocList.as_view(), name='doc_list'),
      url(r'^(\d+)/(?P<pk>\d+)/([^/]+)/$', download, name='doc_download'),
      url(r'^(\d+)/(?P<pk>\d+)/$', send, name='doc_send'),
  ]
  
new_contents: from django.conf.urls import url
  from docs.views import *
  
  urlpatterns = [
      url(r'^(?P<folder_id>\d+)/$', DocList.as_view(), name='doc_list'),
      url(r'^(?P<folder_id>\d+)/(?P<pk>\d+)/(?P<filename>[^/]+)$', download,
          name='doc_download'),
      url(r'^(?P<folder_id>\d+)/(?P<pk>\d+)/send/$', send, name='doc_send'),
  ]
  
subject: Fix doc URLs