old_contents: from django.conf.urls import url, include
  from rest_framework.authtoken.views import obtain_auth_token
  from . import views
  
  api_patterns = [
          url(r'^auth/',
              include('rest_framework.urls', namespace='rest_framework')),
          url(r'^token-auth/', obtain_auth_token, name='api-token-auth'),
          url(r'^users/$', views.UserAPI.as_view(), name='users-api'),
          url(r'^users/(?P<pk>[0-9]+)/$', views.UserDetailAPI.as_view(),
              name='users-detail-api'),
          url(r'^groups/$', views.GroupAPI.as_view(), name='groups-api'),
          ]
  
  urlpatterns = [
          url(r'api/1.0/', include(api_patterns)),
          url(r'^generate_pdf/(?P<bill_id>\d+)$', views.generate_pdf,
              name='generate-pdf'),
          ]
  
new_contents: from django.conf.urls import url, include
  from rest_framework.authtoken.views import obtain_auth_token
  from . import views
  
  api_patterns = [
          url(r'^auth/',
              include('rest_framework.urls', namespace='rest_framework')),
          url(r'^token-auth/', obtain_auth_token, name='api-token-auth'),
          url(r'^users/$', views.UserAPI.as_view(), name='users-api'),
          url(r'^users/(?P<pk>[0-9]+)/$', views.UserDetailAPI.as_view(),
              name='users-detail-api'),
          url(r'^groups/$', views.GroupAPI.as_view(), name='groups-api'),
          url(r'^groups/(?P<pk>[0-9]+)/$', views.GroupDetailAPI.as_view(),
              name='groups-detail-api'),
          ]
  
  urlpatterns = [
          url(r'api/1.0/', include(api_patterns)),
          url(r'^generate_pdf/(?P<bill_id>\d+)$', views.generate_pdf,
              name='generate-pdf'),
          ]
  
subject: add groups-detail-api url for group detail endpoints