use Scalar::Util qw(reftype);
sub copy_and_prune {
   my $item = shift;
   return $item unless defined ref($item);
   if (reftype($item) eq 'HASH') {
       if (1 == keys %$item) {
            # return the one value here
       } else {
           my %ret;
           while (my ($key, $value) = each %$item) {
                 $ret{$key} = copy_and_prune($value);
           }
           return \%ret;
       }
   } elsif ( # other cases ...

}