code: def follow_unfollow(request, content_type_id, object_id, flag, do_follow=True, actor_only=True):
      
      ctype = get_object_or_404(ContentType, pk=content_type_id)
      instance = get_object_or_404(ctype.model_class(), pk=object_id)
  
      # If flag was omitted in url, None will pass to flag keyword argument
      flag = flag or ''
  
      if do_follow:
          actions.follow(request.user, instance, actor_only=actor_only, flag=flag)
          return respond(request, 201)   # CREATED
  
      actions.unfollow(request.user, instance, flag=flag)
      return respond(request, 204)
docs: Creates or deletes the follow relationship between ``request.user`` and the
      actor defined by ``content_type_id``, ``object_id``.