Loop 2 vars 

my @to-five  = 0..5;
my @from-ten = (5..10).reverse;

for flat @to-five Z @from-ten -> Int $i, Int $j {
    say "$i $j"
}

say "--- or ---";

for @from-ten.kv -> Int $i, Int $j {
    say "$i $j"
}

say "--- or ---";

for ^6 -> $i {
    say "$i { 10 - $i }"
}

say "--- or ---";

loop (my $i = 0, my $j = 10; $i <= 5; $i++, $j--) {
    say "$i $j"
}