Latte\Runtime\Filters::substring PHP Method

    public static function substring($s, $start, $length = NULL)
    {
        if ($length === NULL) {
            $length = strlen(utf8_decode($s));
        }
        if (function_exists('mb_substr')) {
            return mb_substr($s, $start, $length, 'UTF-8');
            // MB is much faster
        }
        return iconv_substr($s, $start, $length, 'UTF-8');
    }