my $iterator = &foo();

  while($iterator->()) {
    # do something
  }

##</code><code>##

  sub foo {
    return sub {
      # some code
    };
  }

##</code><code>##

  my $even = &even_numbers(1000);

  while (my $n = $even->()) {
    print "$n\n";
    sleep(1);
  }

  sub even_numbers {
    my $number = shift;
    $number-- unless ($number % 2);

    return sub { $number += 2 };
  }