anchor.diff:           (list 'shared-initialize (class-prototype class) t))
      initargs
      (lambda (valid-initargs invalid-initargs)
  -     (error "Invalid initargs ~:S when creating instance of ~S (~S).~%Supplied: ~:S~%valid:~:S"
  +     (error "Invalid initargs ~:S when creating instance of ~S (~S).~%Supplied: ~:S~%valid: ~:S"
               invalid-initargs class (class-name class) initargs valid-initargs))))
   
   (defgeneric make-instance (class &rest initargs &key &allow-other-keys))
  
positive.code:          (list 'shared-initialize object t))
     initargs
     (lambda (valid-initargs invalid-initargs)
       (error "Invalid initargs ~S when reinitializing ~S (~S).~%Supplied: ~:S~%valid:~:S"
              invalid-initargs object (class-name (class-of object)) initargs valid-initargs))))
  
  (defgeneric reinitialize-instance (instance &key &allow-other-keys))
  
negative.code:          (list 'shared-initialize object added-slots))
     initargs
     (lambda (valid-initargs invalid-initargs)
       (error "Invalid initargs ~:S when updating ~S (~S) for redefined class.~%Supplied: ~:S~%valid: ~:S"
              invalid-initargs object (class-name (class-of object)) initargs valid-initargs))))
  
  (defgeneric update-instance-for-redefined-class (instance added-slots discarded-slots property-list &rest initargs &key &allow-other-keys))
  