old_contents: from django.conf.urls import url, include
  from . import views
  
  urlpatterns = [
      url(r'^generate_pdf/(?P<bill_id>\d+)$', views.generate_pdf,
          name='generate-pdf'),
      url(r'^users/$', views.UserAdmin.as_view(), name='users'),
      url(r'^users/(?P<pk>[0-9]+)/$', views.UserAdminDetail.as_view(), name='user-detail'),
      url(r'^api-auth/', include('rest_framework.urls', namespace='rest_framework'))
      ]
  
new_contents: from django.conf.urls import url, include
  from rest_framework.authtoken.views import obtain_auth_token
  from . import views
  
  urlpatterns = [
      url(r'^generate_pdf/(?P<bill_id>\d+)$', views.generate_pdf,
          name='generate-pdf'),
      url(r'^users/$', views.UserAdmin.as_view(), name='users'),
      url(r'^users/(?P<pk>[0-9]+)/$', views.UserAdminDetail.as_view(), name='user-detail'),
      url(r'^api-auth/', include('rest_framework.urls', namespace='rest_framework')),
      url(r'^api-token-auth/', obtain_auth_token)
      ]
  
subject: Add rest_framework view to obtain auth token