use strict;
use warnings;
##</code><code>##

use strict;
use warnings;

my @sets = (
[0],
[0, 1],
[0, 1, 2],
[1, 2, 3],
[5, 6, 4],
);

my @clusters;

foreach my $set (@sets)
{
  push @clusters, Set::Scalar->new->insert(@$set);
}

for my $i (0.. $#clusters)
{
...

##</code><code>##

0 superclusters: () : adding (0)... 0 intersections.
1 supercluster: ((0)) : adding (1,2,3)... 0 intersections.
2 superclusters: ((0), (1,2,3)) : adding (0,1)... 2 intersections.
1 supercluster: ((0,1,2,3)) : adding (0,1,2)... 1 intersection.