public function setEnvironments($env) {
    $envs = (explode('+', $env));
    while (!empty($envs)) {
      $_env = array_shift($envs);
      if (!$this->setEnvironment($_env)) {
        $msg = dt("Unable to locate an environment definition for '@env'.", ['@env' => $_env]);
        if (empty($envs)) {
          drush_log($msg, 'warning');
          return FALSE;
        }
        else {
          drush_log($msg, 'warning');
          if (!drush_confirm(dt("Do you want to process the other environments?"))) {
            return drush_user_abort(dt("Aborting."));
          }
        }
      }
    }

    return TRUE;
  }