SOLVED validation server side on core organization field signup

<?php /**  * @package            Joomla  * @subpackage         Membership Pro  * @author             Tuan Pham Ngoc  * @copyright          Copyright (C) 2010 - 2018 Ossolution Team  * @license            GNU/GPL, see LICENSE.php  */ defined('_JEXEC') or die; Valitron\Validator::addRule('schoolroll', function($field, $value, array $params, array $fields) {     // Validate for exactly 5 digits followed by a single letter     if (!preg_match('/^\d{5}[A-Za-z]$/', $value)) {         return false;     }     return true; }, 'School Roll is 5 digits followed by 1 letter. WARNING! Accounts with incorrect School Rolls will be removed.'); Valitron\Validator::addRule('rule2', function($field, $value, array $params, array $fields) {     if ($value != 9)     {             return false;     }     return true; }, 'The field must has value = 9');