private function doBatch($method, $request)
    {
        $batchPart = null;
        if ($this->_captureBatch === true) {

            /** @var $batch Batch */
            $batch = $this->getActiveBatch();

            $batchPart = $batch->append($method, $request);
        }

        # do batch processing
        return $batchPart;
    }