anchor.diff:  (defun check-update-instance-for-different-class-initargs (old new initargs)
     (check-initargs
      (class-of new) *u-i-f-d-c-initargs-cache*
  -   (list (list #'update-instance-for-different-class old new)
  -         (list #'shared-initialize new t))
  +   (list (list 'update-instance-for-different-class old new)
  +         (list 'shared-initialize new t))
      initargs
      (lambda (valid-initargs invalid-initargs)
        (error "Invalid initargs ~:S when updating ~S (~S) for different class.~%Supplied: ~:S~%valid:~:S"
  
positive.code: (defun check-reinitialize-instance-initargs (object initargs)
    (check-initargs
     (class-of object) *reinitialize-instance-initargs-cache*
     (list (list #'reinitialize-instance object)
           (list #'shared-initialize object t))
     initargs
     (lambda (valid-initargs invalid-initargs)
       (error "Invalid initargs ~S when reinitializing ~S (~S).~%Supplied: ~:S~%valid:~:S"
  
negative.code: (defun check-update-instance-for-redefined-class-initargs (object added-slots discarded-slots property-list initargs)
    (check-initargs
     (class-of object) *u-i-f-r-c-initargs-cache*
     (list (list 'update-instance-for-redefined-class object added-slots discarded-slots property-list)
           (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"
  