old_contents: from django.conf.urls import url
  from . import views
  
  app_name = 'inventory'
  
  urlpatterns = [
      url(r'^$', views.index, name='index'),
      url(r'^(?P<item_id>[0-9]+)/$', views.detail, name='detail'),
      url(r'^add_item/', views.add_item, name='add_item'),  # TODO
      url(r'^add_tag/', views.add_tag, name='add_tag'),  # TODO
      url(r'^loan/', views.loan, name='loan'),
      url(r'^registered/', views.registered, name='registered'),
      url(r'^(?P<item_id>[0-9]+)/change_item/$', views.change_item, name='change_item'),
  ]
  
new_contents: from django.conf.urls import url
  from . import views
  
  app_name = 'inventory'
  
  urlpatterns = [
      url(r'^$', views.index, name='index'),
      url(r'^(?P<item_id>[0-9]+)/$', views.detail, name='detail'),
      url(r'^add_item/', views.add_item, name='add_item'),  # TODO
      url(r'^(?P<item_id>[0-9]+)/add_item/$', views.add_item, name='add_item'),
  
      url(r'^add_tag/', views.add_tag, name='add_tag'),  # TODO
      url(r'^(?P<tag_id>[0-9]+)/add_tag/$', views.add_tag, name='add_tag'),
      url(r'^(?P<tag_id>[0-9]+)/tag_detail/$', views.tag_detail, name='tag_detail'),
  
      url(r'^loan/', views.loan, name='loan'),
      url(r'^registered/', views.registered, name='registered'),
  ]
  
subject: add url for add_item and tag_detail