my @array = (1,2,3);
    $_ *= 2 for @array;
    print "@array\n";     # prints: 2 4 6

##</code><code>##

    $_ *= 2 for 1,2,3;  # error: modification of read-only value

##</code><code>##

    my @array = (1,2,3);
    for my $e (map $_, @array) {
        $e++; # or whatever
    }
    print "@array\n";