$nl_iter = NestedLoops( \@Loops ); # some fancy magic for \@Loops

while( my @items = $nl_iter->() ) {
    print join ", " @items;
    print "\n";
}

#outputs:
1, y, 7
1, y, 14
1, y, 21
1, y, 28
1, n, 7
1, n, 14
...
3, n, 21
3, n, 28