sub yn {
        my $question = shift; 
        $question ||='Your answer? ';

        my $val = undef;

        until (defined $val){
                print "$question (y/n): ";
                $val = <STDIN>;
                chomp $val;

                # $val = 
                #   $val eq 'y' ? 1 : (
                #      $val eq 'n' ? 0 : undef 
                #   );

                if ($val eq 'y'){ 
                   $val = 1; 
                }

                elsif ($val eq 'n'){ 
                   $val = 0;
                }

                else { 
                   $val = undef; 
                }
        }
        return $val;
}