'Specifying a namespace in include() without providing an app_name ' code example

Example: django.core.exceptions.ImproperlyConfigured: Specifying a namespace in include() without providing an app_name is not supported. Set the app_name attribute in the included module, or pass a 2-tuple containing the list of patterns and app_name instead.

url(r'^reviews/', include(('reviews.urls', 'reviews'), namespace='reviews')),