{
	package Tax::Zone;
	sub new {
		my $class = shift;
		my $rate  = $_[0];
		bless \$rate, $class;
	}
	sub add_tax {
		my $self  = shift;
		my $price = $_[0];
		return $price * (1 + $$self);
	}
}

my $fooland = Tax::Zone->new(0.20);
print $fooland->add_tax(50.00), "\n";

my $barland = Tax::Zone->new(0.15);
print $barland->add_tax(50.00), "\n";