my %couples = (
  george => 'gracie',
  abbot => 'costello',
  johnson => 'boswell',);

while (my($c, $d) = each %couples) {
   print "$c $d\n";
}

print "\n";

foreach my $c (each %couples) {
  print "$c\n";
}

print "\n";

while ( my($c, $d) = each %couples) {
        print "$d $c\n";
}