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.

##</code><code>##

$ perl -le" %f=1..4; while( each %f ){print $g++; } "
0
1

$ perl -le" %f=1..4; while( each %f ){print $g++; keys %f; die if $g > 5; } "
0
1
2
3
4
5
Died at -e line 1.