private function toString($lines = null): string
    {
        // empty path return empty string
        if ($lines === null || count($lines) === 0) {
            return '';
        }

        return implode(
            ' ',
            array_map(
                function ($arg) {
                    return self::quoteArgument($arg, $this->escape);
                },
                $lines
            )
        );
    }