{
    my @c;
    sub counter : lvalue { my $i = shift; $c[$i]++; $c[$i] }
}

print counter(0), "\n" for 1..3;
counter(0) = 10;
print counter(1), "\n" for 1..3;
counter(1) = 100;
print counter(0), "\n";
print counter(1), "\n";