public function rot13()
        {
            $string = $this->get();
            $value = str_rot13($string);
            $this->update($value);
            return $this;
        }
public function rot13()
        {
            $string = $this->get();
            $value = str_rot13($string);
            $this->update($value);
            return $this;
        }
public function rot13 ( ) { $ string = $ this -> get ( ) ; $ value = str_rot13 ( $ string ) ; $ this -> update ( $ value ) ; return $ this ; }
Performs the ROT13 encoding on the str argument and returns the
resulting string.

The ROT13 encoding simply shifts every letter by 13 places in the
alphabet while leaving non-alpha characters untouched. Encoding and
decoding are done by the same function, passing an encoded string as
argument will return the original version.

Obviously this is not for any actual encryption...

@return \PHY\Variable\Str
Performs the ROT13 encoding on the str argument and returns the resulting string .