old_contents: from django.conf.urls import include, url
  from django.contrib import admin
  from core import settings
  admin.site.site_header = 'Coworking space administration'
  
  urlpatterns = [
      url(r'^billjobs/', include('billjobs.urls')),
      url(r'^admin/', include(admin.site.urls)),
  ]
  
  if settings.DEBUG:
      import debug_toolbar
      urlpatterns = [
          url(r'^__debug__/', include(debug_toolbar.urls)),
      ] + urlpatterns
  
new_contents: from django.conf.urls import include, url
  from core import settings
  from billjobs.admin import admin_site
  admin_site.site_header = 'Coworking space administration'
  
  urlpatterns = [
      url(r'^billjobs/', include('billjobs.urls')),
      url(r'^admin/', include(admin_site.urls)),
  ]
  
  if settings.DEBUG:
      import debug_toolbar
      urlpatterns = [
          url(r'^__debug__/', include(debug_toolbar.urls)),
      ] + urlpatterns
  
subject: use BilljobsAdminSite