old_contents: from django.conf.urls import url, include
  
  from . import views
  from .views import router
  
  urlpatterns = [
      url(r'^$', views.index, name='index'),
      url(r'^backend/', include(router.urls))
  ]
  
new_contents: from django.conf.urls import url, include
  
  from . import views
  from .views import router
  
  urlpatterns = [
      url(r'^$', views.index, name='index'),
      url(r'^api/v1/', include(router.urls))
  ]
  
subject: update endpoint