anchor.diff:    iter)
   
   (defclass list-iter (iter)
  -  (.list
  -   .i))
  +  (list
  +   i))
   
   (defun list-iter ((list list))
     (let ((iter (make list-iter)))
  
positive.code: (defclass control-error (error))
  
  (defclass restart (condition)
    (.associated-condition))
  
  ;;; Specific restarts
  (defclass abort (restart))
  (defclass continue (restart))
  (defclass use-value (restart)
    (.value))
  (defclass store-value (restart)
    (.value))
  
  (defgeneric default-handler (condition))
  (defmethod default-handler ((c condition))
  
negative.code:       #',name))
  
  (defmacro defslot (slot class)
    (let* ((slot-name (symbol-name slot))
           (accessor-name (string-concat "." slot-name))
           (setter-name (setter-name accessor-name))
           (slot-name-form (string-to-form slot-name)))
      #`(progn
          (defmethod ,(string-to-symbol accessor-name) ((obj ,class))
            (slot-value obj ,slot-name-form))
          (defmethod ,(string-to-symbol setter-name) ((obj ,class) value)
            (set-slot-value obj ,slot-name-form value)))))
  