anchor.diff:  (defclass class (specializer)
     ((%unique-number 
       :initform (prog1 *class-unique-number* (incf *class-unique-number*))
  -    :reader unique-number)
  +    :accessor unique-number)
      (%name 
       :initform nil
       :initarg :name 
  
positive.code: ;;;
  ;;; The MOP class hierarchy. 
  
  (defconstant +timestamp-offset+ 0)
  (defconstant +instance-slots-offset+ 1)
  
  (define-built-in-class t () ())
  
negative.code: (define-built-in-class function (t) ())
  
  (defclass standard-object (t)
    (;; We keep a copy of the effective slots of the class that were
     ;; used to create an instance.  They are used when the instance
     ;; needs to be updated because the class has changed, and it may
     ;; also be used by the garbage collector for type information of
  