old_contents: from django.apps import AppConfig
  
  from django.db.models.signals import pre_save, post_save
  from django.contrib.sites.models import Site
  
  
  class SitesConfig(AppConfig):
      name = 'openedx.core.djangoapps.appsembler.sites'
      label = 'appsembler_sites'
  
      def ready(self):
          from .models import patched_clear_site_cache
  
          pre_save.connect(patched_clear_site_cache, sender='site_configuration.SiteConfiguration')
  
new_contents: from django.apps import AppConfig
  
  from django.db.models.signals import pre_save, post_save
  
  
  class SitesConfig(AppConfig):
      name = 'openedx.core.djangoapps.appsembler.sites'
      label = 'appsembler_sites'
  
      def ready(self):
          from .models import patched_clear_site_cache
  
          pre_save.connect(patched_clear_site_cache, sender='site_configuration.SiteConfiguration')
  
subject: remove an import that isn't used