sub pro {
    my $self = shift;
    
    sub attr {
        my $node = shift;
        my $map = $node->getAttributes;
        
        my @tmp = %$map;

        while ( my ( $key, $value ) = each %$map ) {
            next unless ( ref( $value ) eq 'XML::DOM::Attr' );
            my $val = $value->getValue;
            return "\[\@$key=\'$val\'\]";
        }
        return undef;
    }

    sub trace {
        my $node = shift;
        my $attr = attr($node);

        # base case
        if ( $node->getParentNode->getNodeType == 9 ) {
            $attr ?
               
 return "//" . $node->getNodeName . $attr :
               
 return "//" . $node->getNodeName;
        }

        # return unique path
        $attr ?    
            return trace( $node->getParentNode ) . "/" . $node->getNodeName . $attr :
            return trace( $node->getParentNode ) . "/" . $node->getNodeName;
    }

    # "main"
    my @paths = map { trace($_) } $self->{'xml1'}->findnodes( '//*' );
    print join "\n", @paths;
    exit;
    for my $path ( @paths ) {
        print "\nPath: ", $path;
        for ( $self->{'xml2'}->findnodes( $path ) ) {
            print "\nFound node: ", $_->getNodeName;
            print "\thas Value: ", $_->getFirstChild->getNodeValue if $_->getFirstChild;
        }
    }
}