code: def search_form(context, search_model_names=None):
      
      template_vars = {
          "request": context["request"],
      }
      if not search_model_names or not settings.SEARCH_MODEL_CHOICES:
          search_model_names = []
      elif search_model_names == "all":
          search_model_names = list(settings.SEARCH_MODEL_CHOICES)
      else:
          search_model_names = search_model_names.split(" ")
      search_model_choices = []
      for model_name in search_model_names:
          try:
              model = apps.get_model(*model_name.split(".", 1))
          except LookupError:
              pass
          else:
              verbose_name = model._meta.verbose_name_plural.capitalize()
              search_model_choices.append((verbose_name, model_name))
      template_vars["search_model_choices"] = sorted(search_model_choices)
      return template_vars
docs: Includes the search form with a list of models to use as choices
      for filtering the search by. Models should be a string with models
      in the format ``app_label.model_name`` separated by spaces. The
      string ``all`` can also be used, in which case the models defined
      by the ``SEARCH_MODEL_CHOICES`` setting will be used.