text: """
  Add a many-to-many relationship field to relate this page to other pages.
  """
  
  from __future__ import absolute_import, unicode_literals
  
  from django.db import models
  from django.utils.translation import gettext_lazy as _
  
  from feincms import extensions, settings
  
  
  class Extension(extensions.Extension):
      def handle_model(self):
          self.model.add_to_class(
              "related_pages",
              models.ManyToManyField(
                  settings.FEINCMS_DEFAULT_PAGE_MODEL,
                  blank=True,
                  related_name="%(app_label)s_%(class)s_related",
                  help_text=_("Select pages that should be listed as related content."),
              ),
          )
  
      def handle_modeladmin(self, modeladmin):
          modeladmin.extend_list("filter_horizontal", ["related_pages"])
  
          modeladmin.add_extension_options(
              _("Related pages"), {"fields": ("related_pages",), "classes": ("collapse",)}
          )
  