my($hf) = File::Util->;new();
my(@HighFolders) = $hf->;list_dir($Highpath,'--dirs-only');

##</code><code>##

#!/usr/bin/perl -w
use strict;

use File::Util;

my $hf = File::Util->new();
my $path = '/';
my @Folders;

foreach ($hf->list_dir($path,'--dirs-only')) {
	my @tmp = $_;
	push @Folders, \@tmp;	# the outer array ref
}

foreach (@Folders) {
	my $lf = File::Util->new();
	my @tmp = $lf->list_dir($path.$_->[0],'--dirs-only');
	$_->[1] = \@tmp;	# inner array ref
}

# verify:
foreach (@Folders) {
	print $_->[0]."\n";
	foreach my $sub (@{$_->[1]}) {
		print "\t$sub\n";
	}
}

##</code><code>##

my @Folders;   
# array of array refs, each sub-array =
# 0: directory name
# 1: array of subdirectories