package Filter::ISA;
use strict;
use warnings;

use Filter::Simple;

FILTER_ONLY code => sub {
  s/package\s+(\w+?)\s+isa\s+(.+?);/"package $1; use base qw( " . join(" ", split(",", $2)) . " );"/eg;
};

1;

##</code><code>##

use Filter::ISA;

package derived isa base1, base2;