my @x = 1 .. 5;
sub get_x { @x }
foreach my $v ( get_x() ) {
    $v *= 2;
}
print "@x\n";

##</code><code>##

while (my ($k, $v) = each %hash) {
    $hash{ $k . 'a' } = 1;
}

foreach my $k (keys %hash) {
    $hash{ $k . 'a' } = 1;
}