my %hash = 1..4;
my $stop = 0;
while( my( $k, $v ) = each %hash ){
   $stop++;
   print "# $k $v\n";
   while( my( $kk, $vv ) = each %hash ){
       print "## $kk $vv\n";
   }
   die if $stop > 2;
}
__END__
# 1 2
## 3 4
# 1 2
## 3 4
# 1 2
## 3 4
Died at - line 9.