Progress bar Example: drush command drupal 8

MigrateOPMCommands.php

<?php

namespace Drupal\migrate_opm\Commands;

use Drush\Commands\DrushCommands;
use Symfony\Component\Console\Helper\ProgressBar;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;
/**
 * A Drush commandfile.
 *
 * In addition to this file, you need a drush.services.yml
 * in root of your module, and a composer.json file that provides the name
 * of the services file to use.
 */
class MigrateOPMCommands extends DrushCommands {

  /**
   * Constructs a new DepotService object.
   */
  public function __construct() {
  }

  /**
   * Main command.
   *
   * @param \Symfony\Component\Console\Input\InputInterface $input
   *   Input.
   * @param \Symfony\Component\Console\Output\OutputInterface $output
   *   Output.
   *
   * @command migrate_opm:progress-bar
   * @aliases opm-insert-users
   * @usage migrate_opm:insert-users
   */
  public function show_progress_bar(InputInterface $input, OutputInterface $output) {
    $progressBar = new ProgressBar($output, 100);
    $progressBar->start();
    for ($i = 1; $i <= 100; $i++) {
      usleep(500000);
      $progressBar->advance();
    }
    $progressBar->finish();
  }

}