package Encode::ROT13;
use strict;
use warnings;

use parent qw( Encode::Encoding );

sub encode($$;$){
  my( $obj, $str, $chk ) = @_;
  $str =~ tr/A-Za-z/N-ZA-Mn-za-m/;
  $_[1] = '' if $chk; # $_[1] is aliased through the call. Inplace edit.
                      # (Remove whole string unless there's an error.)
  return $str;
}

no warnings 'once';
*decode = \&encode; # Because rot13( rot13() ) is a round-trip.

__PACKAGE__->Define( 'rot13' );

1;


package main;

use strict;
use warnings;

binmode \*DATA, ':encoding(rot13)';

chomp( my @words = <DATA> );

print "$_\n" for @words;

__DATA__
Apple
cat
dog
strawberry
watermelon

##</code><code>##

Nccyr
png
qbt
fgenjoreel
jngrezryba