hospital_management-8.x-1.x-dev/web/modules/hms/hms_appointments/src/Controller/AppointmentsController.php

<?php

namespace Drupal\hms_appointments\Controller;

use Drupal\Core\Controller\ControllerBase;

/**
 * Class AppointmentsController.
 */
class AppointmentsController extends ControllerBase {

  /**
   * Addappointment.
   *
   * @return string
   *   Return Hello string.
   */
  public function addAppointment() {
    return [
      '#type' => 'markup',
      '#markup' => $this->t('Implement method: addAppointment')
    ];
  }

}