anchor.diff:        (cdr form)
       (with-form-object (throw throw-form :parent parent :source form)
         (setf (tag throw) (walk-form tag throw env)
  -            (value throw) (walk-form result throw env)))))
  +            (value-of throw) (walk-form result throw env)))))
   
   ;;;; EVAL-WHEN
   
  
positive.code: ;;;; LOAD-TIME-VALUE
  
  (defclass load-time-value-form (form)
    ((value :accessor value)
     (read-only-p :accessor read-only-p)))
  
  (defwalker-handler load-time-value (form parent env)
    (with-form-object (load-time-value load-time-value-form
                                       :parent parent :source form)
      (setf (value load-time-value) (walk-form (second form) load-time-value env)
            (read-only-p load-time-value) (third form))))
  
  ;;;; LOCALLY
  
negative.code: 
  (defclass the-form (form)
    ((type :accessor type-of :initarg :type)
     (value :accessor value-of :initarg :value)))
  
  (defwalker-handler the (form parent env)
    (with-form-object (the the-form :parent parent :source form
                                    :type (second form))
      (setf (value-of the) (walk-form (third form) the env))))
  
  ;;;; UNWIND-PROTECT
  
  