code: def start_decoder(self, checkpoint: int):
          
          assert self.decoder_process is None
          output_name = os.path.join(self.output_folder, C.DECODE_OUT_NAME % checkpoint)
          self.decoder_process = self.ctx.Process(target=_decode_and_evaluate,
                                                  args=(self.decoder, checkpoint, output_name, self.decoder_metric_queue))
          self.decoder_process.name = 'Decoder-%d' % checkpoint
          logger.info("Starting process: %s", self.decoder_process.name)
          self.decoder_process.start()
          self._results_pending = True
docs: Starts a new CheckpointDecoder process and returns. No other process may exist.
  
          :param checkpoint: The checkpoint to decode.