anchor.diff:                         ((is-operator)
                           (make-operator word))
   
  +                       ((reserved-p word)
  +                        (make-reserved word))
  +
                          ((and (not (find-if-not #'digit-char-p word))
                                (or (equal #\< next-char) (equal #\> next-char)))
                           (make-instance 'io-number :value word))
   
                          (t
  -                        (make-instance 'token :value word))))))
  +                        (make-instance 'a-word :value word))))))
   
         (macrolet ((again () '(return-from again)))
   
  
positive.code:   (find char '(#\space #\tab #\linefeed #\return)))
  
  (defun token-iterator (stream)
    (let (hit-eof)
      (make-iterator ()
        (when hit-eof
          (stop))
        (let ((token (next-token stream)))
          (when (typep token 'eof)
            (setf hit-eof t))
          (emit token)))))
  
  (defgeneric tokenize (source))
  
  
negative.code:     (loop :while (not (typep token 'eof)) :do
         (progn (vector-push-extend token result)
                (setf token (next-token stream))))
      result))
  
  (defun next-token (stream)
  