sub hash {
        my $h = shift;
        return %$h;
}

sub href {
        my $h = shift;
        return $h;
}

my $n = { moo => 'blah', arrg => 'no' };
my %hash = hash($n);
$hash{arrg} = 'yes';
print join(' ',%$n) . "\n";
# Output: moo blah arrg no

my $m = { moo => 'blah', arrg => 'no' };
my $hash = href($m);
$hash->{arrg} = 'yes';
print join(' ',%$m) . "\n";
# Output: moo blah arrg yes