sub explorenode {
    my ( $node, $rows, $left, $id ) = @_;
    my $i = $id;
    my $l = $left;
    for ( 2 .. $#$node ) {
        $id++;
        $left++;
        explorenode( $node->[$_], $rows, $left, $id );
        $id++;
        $left++;
    }
    $left++;
    push( @$rows, [ $i, $l, $left, $node->[0], $node->[1] ] );
}