my $depth = 4;
my $loop = [[0..1]];
my $val = 3;
for my $i (1..$depth-1) {
    push @$loop, sub {[$_+1..$val]};
    $val+=2;
}
my $iter = NestedLoops($loop);
while (my @list = $iter->()) {
  output(@list);
}

sub output {
  my @args = @_;
  print join '', @args, "\n";
}