sub do_something
{
    my $h = shift;

    print '1. do_something(): ' . $h . "\n";

    %{ $h } = ( a => 'alpha', b => 'beta' );

    print '2. do_something(): ' . $h . "\n";
    print Dumper( $h );
}

##</code><code>##

hash = HASH(0x490d30)
1. do_something(): HASH(0x490d30)
2. do_something(): HASH(0x490d30)
{
  'a' => 'alpha',
  'b' => 'beta'
}
{
  'a' => 'alpha',
  'b' => 'beta'
}