anchor.diff:  
   ;;;; This file contains very basic versions of the functions
   ;;;; ADD-READER-METHOD and ADD-WRITER-METHOD.  These functions are not
  -;;;; part of the spcification, but they conventient abstractions that
  +;;;; part of the specification, but they convenient abstractions that
   ;;;; are called when a class metaobject is created that has one or
   ;;;; more slots with a :READER, :WRITER, or :ACCESSOR slot option.
   ;;;; Specifically, they are called from the :AFTER methods on
   ;;;; INITIALIZE-INSTANCE specialized for STANDARD-CLASS and
   ;;;; FUNCALLABLE-STANDARD-CLASS.
  +
  +;;; The functions defined here need to call ENSURE-GENERIC-FUNCTION to
  +;;; make sure the generic function on which a method is going to be
  +;;; added exists.  However, we do not call ENSURE-GENERIC-FUNCTION
  +;;; directly, because during bootstrapping, we need to do different
  +;;; things in phase 1 and phase 2.  For that reason, we call an
  +;;; intermediate function named ENSURE-ACCESSOR-FUNCTION, and make
  +;;; that function mean different things in phase 1 and phase 2.
   
   ;;; Add a reader method to a generic function.  CLASS is a class
   ;;; metaobject that plays the role of specialize for the argument of
  
positive.code: ;;; method for optimization purposes. 
  (defun add-reader-method (class function-name slot-definition)
    (let* ((lambda-list '(object))
  	 (generic-function (ensure-accessor-function function-name lambda-list))
  	 (specializers (list class))
  	 (method-function
  
negative.code: ;;; method for optimization purposes.
  (defun add-writer-method (class function-name slot-definition)
    (let* ((lambda-list '(new-value object))
  	 ;; See comment above as to why we do not call
  	 ;; ENSURE-GENERIC-FUNCTION directly here.
  	 (generic-function (ensure-accessor-function function-name lambda-list))
  	 (specializers (list *t* class))
  	 (method-function
  