% reply 0> use RememberingSet 1> my $s = RememberingSet->new $res[0] = bless( { '_count' => {}, '_items' => {} }, 'RememberingSet' ) 2> $s->has(1) $res[1] = '' 3> $s->add(1) $res[2] = 1 4> $s->seen(1) $res[3] = 3