public static function inspect(vfsStreamVisitor $visitor, vfsStreamContent $content = null): vfsStreamVisitor
    {
        if (null !== $content) {
            return $visitor->visit($content);
        }

        $root = vfsStreamWrapper::getRoot();
        if (null === $root) {
            throw new \InvalidArgumentException('No content given and no root directory set.');
        }

        return $visitor->visitDirectory($root);
    }