old_contents: from django.conf.urls import url
  from django.contrib import admin
  
  from .views import ArticleView, PageView
  
  
  urlpatterns = [
      url(r"^admin/", admin.site.urls),
      url(r"^articles/(?P<pk>\d+)/$", ArticleView.as_view(), name="article_detail"),
      url(r"^pages/(?P<pk>\d+)/$", PageView.as_view(), name="page_detail"),
  ]
  
new_contents: from django.urls import re_path
  from django.contrib import admin
  
  from .views import ArticleView, PageView
  
  
  urlpatterns = [
      re_path(r"^admin/", admin.site.urls),
      re_path(r"^articles/(?P<pk>\d+)/$", ArticleView.as_view(), name="article_detail"),
      re_path(r"^pages/(?P<pk>\d+)/$", PageView.as_view(), name="page_detail"),
  ]
  
subject: Switch from url() to re_path()