old_contents: from django.conf.urls import url
  from rest_framework import routers
  
  from .views import AccountView, CreditCardViewSet
  
  router = routers.SimpleRouter(trailing_slash=False)
  router.register(r'account/credit-cards', CreditCardViewSet, base_name='billing_creditcard')
  
  urlpatterns = router.urls + [
      url(r'^account$', AccountView.as_view(), name='billing_account'),
  ]
  
new_contents: from django.conf.urls import url
  from rest_framework import routers
  
  from .views import AccountView, CreditCardViewSet
  
  router = routers.SimpleRouter(trailing_slash=False)
  router.register(r'account/credit-cards', CreditCardViewSet, basename='billing_creditcard')
  
  urlpatterns = router.urls + [
      url(r'^account$', AccountView.as_view(), name='billing_account'),
  ]
  
subject: fix deprecation warning