public static function _doModifySquad()
 {
     $params = ['id' => $_POST['squad_id'], 'leader_id' => $_POST['leader_id']];
     Squad::modify($params);
     // update member position, squad id
     if ($params['leader_id']) {
         $params = ['id' => $params['leader_id'], 'position_id' => 5, 'squad_id' => 0];
         Member::modify($params);
     }
 }