#!/usr/bin/perl -w
                                                                                
use strict;
use warnings;
use Data::Dumper;
                                                                                
my %hash;
my ($w1, $w2, $w3) = ("blue", "marbles", "lottery");
my $count      = 17;
my $tot_counts = 42;
                                                                                
$hash{$w1}{$w2} = {
    total_counts => $tot_counts,
    words => { $w3 => $count }
};
                                                                                
# Use the reference of the hash (\%hash) rather than
# just the hash values (%hash).
#
print Dumper(\%hash);

__END__

== Output ==
$VAR1 = {
          'blue' => {
                      'marbles' => {
                                     'total_counts' => 42,
                                     'words' => {
                                                  'lottery' => 17
                                                }
                                   }
                    }
        };

##</code><code>##

#!/usr/bin/perl -w
                                                                                
use strict;
use warnings;
use Data::Dumper;
                                                                                
my %hash = ( 'test', 'program' );
print Dumper($hash);                #  Error: should be \%hash
                                                                                
__END__
== Output ==
Global symbol "$hash" requires explicit package name at hash_test line 8.