old_contents: # ------------------------------------------------------------------------
  # coding=utf-8
  # ------------------------------------------------------------------------
  
  from __future__ import absolute_import
  
  from django.contrib import admin
  
  from .models import Page
  from .modeladmins import PageAdmin
  
  # ------------------------------------------------------------------------
  admin.site.register(Page, PageAdmin)
  
  # ------------------------------------------------------------------------
  # ------------------------------------------------------------------------
  
new_contents: # ------------------------------------------------------------------------
  # coding=utf-8
  # ------------------------------------------------------------------------
  
  from __future__ import absolute_import
  
  from django.contrib import admin
  from django.core.exceptions import ImproperlyConfigured
  from django.db.models import FieldDoesNotExist
  
  from .models import Page
  from .modeladmins import PageAdmin
  
  # ------------------------------------------------------------------------
  try:
      Page._meta.get_field('template_key')
  except FieldDoesNotExist:
      raise ImproperlyConfigured(
          'The page module requires a \'Page.register_templates()\' call somewhere'
          ' (\'Page.register_regions()\' is not sufficient).')
  
  admin.site.register(Page, PageAdmin)
  
  # ------------------------------------------------------------------------
  # ------------------------------------------------------------------------
  
subject: Abort when the page model does not have a template_key field