old_contents: from django.conf.urls import url
  
  from posts.api import *
  
  
  urlpatterns = [
      url(r'^posts/$', PostListAPIView.as_view()),
  ]
  
new_contents: from django.conf.urls import url, include
  
  from posts.api import *
  
  
  urlpatterns = [
      url(r'^posts/', include([
          url(r'^$', PostListAPIView.as_view(), name="list"),
      ], namespace="posts")),
  ]
  
subject: refactor api urls