anchor.diff:    (:nicknames #:enigma)
     (:use :cl)
     (:export #:machine
  +           #:set-rotor
              #:make-rotor
              #:make-reflector
              #:*alphabet*
  
positive.code: ;;;; Last modified : 2013-08-03 13:45:39 tkych
  
  ;; cl-enigma/enigma.lisp
  
  
negative.code:        :for char-num := (position char *alphabet* :test #'char-equal)
         :do (progn
               (when (turnover-p middle-rotor)
                 (rotate left-rotor)
                 ;; double stepping
                 (rotate middle-rotor))
               (when (turnover-p right-rotor)
                 (rotate middle-rotor))
               (rotate right-rotor))
  