text: from django.apps import AppConfig, apps
  from django.core.exceptions import ImproperlyConfigured
  from django.utils.translation import ugettext_lazy as _
  
  
  class FilerVersioningPicturePluginAppConfig(AppConfig):
      name = 'djangocms_versioning_filer.plugins.picture'
      verbose_name = _('django CMS versioning filer picture plugin')
  
      def ready(self):
          try:
              apps.get_app_config('djangocms_versioning_filer')
              apps.get_app_config('djangocms_picture')
          except LookupError:
              raise ImproperlyConfigured(
                  'djangocms_versioning_filer or djangocms_picture not found in INSTALLED_APPS. Please '
                  'add that two apps above {}'.format(self.name)
              )
  