sub generateSequencer {
    my( $start, $inc )= @_;
    $start -= $inc;
    return sub { return $start += $inc; };
}

my $countByTwos= generateSequencer( 0, 2 );
print $countByTwos->(), $/   for   1..3;
my $countByThrees= generateSequencer( 1, 3 );
print $countByTwos->(), " ", $countByThrees->(), $/
    for   1..4;