old_contents: from django.conf.urls import url
  from .views import LoginPage, ClientCreateView, ClientListView
  from django.contrib.auth.views import logout_then_login
  
  urlpatterns = [
      url(r'^$', ClientListView.as_view(), name='ClientListView'),
      url(r'^add$', ClientCreateView.as_view(), name='ClientCreateView'),
      url(r'^login/', LoginPage.as_view(), name='LoginPage'),
      url(r'^logout/', logout_then_login, name='LogoutPage'),
  ]
  
new_contents: from django.conf.urls import url
  from .views import LoginPage, ClientCreateView, ClientListView, ClientDetailView
  from django.contrib.auth.views import logout_then_login
  
  urlpatterns = [
      url(r'^$', ClientListView.as_view(), name='ClientListView'),
      url(r'^add$', ClientCreateView.as_view(), name='ClientCreateView'),
      url(r'^clients/(?P<pk>[^/]+)/', ClientDetailView.as_view(), name='ClientDetailView'),
      url(r'^login/', LoginPage.as_view(), name='LoginPage'),
      url(r'^logout/', logout_then_login, name='LogoutPage'),
  ]
  
subject: Add ClientDetailView Routing