public static function startsWith($str, $find, $match_case = true)
    {
        if ($match_case) {
            return self::$use_mbstring
                ? mb_strpos($str, $find) === 0
                : strpos($str, $find) === 0;
        } else {
            return self::$use_mbstring
                ? mb_stripos($str, $find) === 0
                : stripos($str, $find) === 0;  
        }
    }