old_contents: from django.conf.urls import url
  from django.contrib import admin
  from django.http import HttpResponse
  
  
  urlpatterns = [
      url(r'^$', lambda request, *args, **kwargs: HttpResponse()),
      url(r'^admin/', admin.site.urls),
  ]
  
new_contents: from django.urls import re_path
  from django.contrib import admin
  from django.http import HttpResponse
  
  
  urlpatterns = [
      re_path(r'^$', lambda request, *args, **kwargs: HttpResponse()),
      re_path(r'^admin/', admin.site.urls),
  ]
  
subject: Replace url() with re_path() available in newer Django