old_contents: from django.conf.urls import include, url
  from django.views.generic import TemplateView
  
  
  urlpatterns = [
      url(r"^comment/", include("pinax.comments.urls")),
      url(r"^demo/$", TemplateView.as_view(), name="demo_detail"),
  ]
  
new_contents: from django.conf.urls import include, url
  from django.views.generic import TemplateView
  
  urlpatterns = [
      url(r"^comment/", include("pinax.comments.urls", namespace="pinax_comments")),
      url(r"^demo/$", TemplateView.as_view(), name="demo_detail"),
  ]
  
subject: add namespace to avoid url include error