use strict;
use warnings;
use Set::Scalar;

my $a1   = Set::Scalar->new(qw(0 1 2 3 4 5 6 7));
my $a2   = Set::Scalar->new(qw(6 7));
my $diff = $a1->difference($a2);

print $diff;

##</code><code>##

19:16 >perl 1718_SoPW.pl
(0 1 2 3 4 5)
19:16 >