package MyLib;
use strict; use warnings;

sub get_data {
    my %hash = (
        A => {
            a => 1,
            b => 2,
        },
        B => {
            a => 3,
            b => 4,
        },
    );

    return \%hash;
}

1;

##</code><code>##

use strict; use warnings;
use MyLib;

my $hashref = MyLib::get_data();
my %hash = %{ $hashref };
for my $key ( keys %hash ) {
    printf( 'Value of `a` in %s is %s', $key, $hash{ $key }->{'a'} );
}

__END__

##</code><code>##

---
A:
    a: 1
    b: 2
B:
    a: 3
    b: 4

##</code><code>##

use strict; use warnings;
use YAML qw/ LoadFile /;

my $hashref = LoadFile('my_data.yaml');
my %hash = %{ $hashref };
for my $key ( keys %hash ) {
    printf( "Value of `a` in %s is %s', $key, $hash{ $key }->{'a'} );
}

__END__