code: def _get_sorting_message(request, key):
          control_list = []
          reverse = request.url.query.get('reverse', None)
          if reverse is None:
              return control_list
          if reverse.lower() == "":
              control_list.append(client_list_control_pb2.ClientSortControls(
                  reverse=True,
                  keys=key.split(",")
              ))
          elif reverse.lower() != 'false':
              control_list.append(client_list_control_pb2.ClientSortControls(
                  reverse=True,
                  keys=reverse.split(",")
              ))
          return control_list