my $h = {'a'=>1, 'b'=>2, 'c'=>3, 'd'=>4,};

 while( my ($k1, $v1) = each(%$h))
        {
         say "external $k1 => $v1";
         while( my ($k2, $v2) = each(%$h))
                {
                 say "internal $k2 => $v2";
                }
        }