anchor.diff:      (:metaclass (list ':metaclass `(find-class ',(cadr option))))
       (:default-initargs (list ':direct-default-initargs
                                `(list ,@(mop-mapappend #'(lambda (x) x)
  -                                                  (mapplist #'(lambda (key value)
  -                                                                `(',key ,value))
  -                                                            (cdr option))))))
  +                                                  (mop-mapplist #'(lambda (key value)
  +                                                                    `(',key ,value))
  +                                                                (cdr option))))))
       (otherwise (list `',(car option) `',(cadr option)))))
   
   (defun mop-canonicalize-defclass-options (options)
     (mop-mapappend #'mop-canonicalize-defclass-option options))
  -
  -; Stub
  -(defun mop-make-instance (class-name &rest all-keys)
  -  (list class-name all-keys))
  -
  -;-------------------------------------------------------------------------------
  -; Glue layer.
  -;-------------------------------------------------------------------------------
   
   (defun mop-ensure-class (name &rest all-keys)
     (if (mop-find-class name nil)
  
positive.code: ; PERFORMANCE OF THIS SOFTWARE.
  
  ;-------------------------------------------------------------------------------
  ; Behavior/support/utility layer.
  ;-------------------------------------------------------------------------------
  
  (defmacro mop-push-on-end (value location)
  
negative.code:         (setf (car (cdr x)) new-value)
          (return-from body new-value)))
      (mop-push-on-end key plist)
      (mop-push-on-end new-value plist)
      new-value))
  
  (defun mop-mapappend (fun &rest args)
  