code: def update_time(sender, **kwargs):
      
      comment = kwargs['instance']
      if comment.content_type.app_label == "happenings" and comment.content_type.name == "Update":
          from .models import Update
          item = Update.objects.get(id=comment.object_pk)
          item.save()
docs: When a Comment is added, updates the Update to set "last_updated" time