use strict;
use warnings;
use Storable;

my %h2;
my %hash = (

	'roster' => {
		'mike'  => 'biology',
		'carol' => 'math',
		'tom'   => 'history',
	},

	'courses' => {
		'math'    => 'full',
		'biology' => 'open',
		'art'     => 'open',
	}
);

store( \%hash, "test.dat" );
%h2 = %{ retrieve "test.dat" };

for ( sort keys %h2 ) {
	print "$_: @{[values %{$h2{$_}}]}\n";
}