anchor.diff:    iter)
   
   (defclass list-iter (iter)
  -  (.list
  -   .i))
  +  (list
  +   i))
   
   (defun list-iter ((list list))
     (let ((iter (make list-iter)))
  
positive.code:   (error (make control-error)))
  
  (defclass handler ()
    (.handler-class
     .handler-function
     .associated-condition))
  
  (defmethod show-object ((h handler))
    (show-object (.handler-class h)))
  
negative.code:         "")))
  
  (defclass number-iter (iter)
    (i
     max))
  
  (defun make-number-iter (max)
    (let ((iter (make number-iter)))
  