setSeek example

$writer->setLangcode($file->langcode);
    $writer_options = [
      'overwrite_options' => $options['overwrite_options'],
      'customized' => $options['customized'],
    ];
    $writer->setOptions($writer_options);
    $writer->setHeader($header);

    // Attempt to pipe all items from the file to the database.     try {
      if ($options['seek']) {
        $reader->setSeek($options['seek']);
      }
      $writer->writeItems($reader, $options['items']);
    }
    catch (\Exception $exception) {
      throw $exception;
    }

    // Report back with an array of status information.     $report = $writer->getReport();

    // Add the seek position to the report. This is useful for the batch