code: def _get_marker_output(self, asset_quantities, metadata):
          
          payload = openassets.protocol.MarkerOutput(asset_quantities, metadata).serialize_payload()
          script = openassets.protocol.MarkerOutput.build_script(payload)
          return bitcoin.core.CTxOut(0, script)
docs: Creates a marker output.
  
          :param list[int] asset_quantities: The asset quantity list.
          :param bytes metadata: The metadata contained in the output.
          :return: An object representing the marker output.
          :rtype: TransactionOutput