static private function _checkData($arr, $v) 
    {
        foreach($arr as $key=>$value)
        {
            if(!is_array($key)) { 
                if ($res = static::_checkString($key, $v)) {
                    return $res;
                }
            } else { 
                if ($res = static::_checkData($key, $v)) {
                    return $res;
                }
            }
            
            if(!is_array($value)) { 
                if ($res = static::_checkString($value, $v)) {
                    return $res;
                }
            } else { 
                if ($res = static::_checkData($value, $v)) {
                    return $res;
                }
            }
        }
        
        return null;
    }