selection example

$regions = [];
    $requirements = update_check_requirements();
    $severity = drupal_requirements_severity($requirements);
    if ($severity == REQUIREMENT_ERROR || ($severity == REQUIREMENT_WARNING && !$request->getSession()->has('update_ignore_warnings'))) {
      $regions['sidebar_first'] = $this->updateTasksList('requirements');
      $output = $this->requirements($severity, $requirements, $request);
    }
    else {
      switch ($op) {
        case 'selection':
          $regions['sidebar_first'] = $this->updateTasksList('selection');
          $output = $this->selection($request);
          break;

        case 'run':
          $regions['sidebar_first'] = $this->updateTasksList('run');
          $output = $this->triggerBatch($request);
          break;

        case 'info':
          $regions['sidebar_first'] = $this->updateTasksList('info');
          $output = $this->info($request);
          break;