old_contents: from django.conf.urls import include, url
  
  from .views import TopicList, TopicDetails, CategoryList, CategoryDetails
  
  app_name = 'drf-spirit'
  
  topic_urls = [
      url(r'^$', TopicList.as_view(), name='topic-list'),
      url(r'^(?P<pk>\d+)/$', TopicDetails.as_view(), name='topic-detail')
  ]
  
  category_urls = [
      url(r'^$', CategoryList.as_view(), name='category-list'),
  ]
  
  
  urlpatterns = [
      url(r'^topics/$', include(topic_urls)),
      url(r'^category/$', include(category_urls)),
  
new_contents: from django.conf.urls import include, url
  
  from .views import TopicList, TopicDetails, CategoryList, CategoryDetails
  
  app_name = 'drf-spirit'
  
  topic_urls = [
      url(r'^$', TopicList.as_view(), name='topic-list'),
      url(r'^(?P<pk>\d+)/$', TopicDetails.as_view(), name='topic-detail')
  ]
  
  category_urls = [
      url(r'^$', CategoryList.as_view(), name='category-list'),
      url(r'^(?P<pk>\d+)/$', CategoryDetails.as_view(), name='category-detail')
  ]
  
  
  urlpatterns = [
      url(r'^topics/$', include(topic_urls)),
      url(r'^category/$', include(category_urls)),
  
subject: fix CategoryDetails url