anchor.diff:     (constructor #'initialize-auto-mode)))
   
   (defmethod non-rememberable-modes ((auto-mode auto-mode))
  -  (mapcar #'mode-invocation (slot-value auto-mode 'non-rememberable-modes)))
  +  (mode-invocations (slot-value auto-mode 'non-rememberable-modes)))
   
   (define-command save-non-default-modes-for-future-visits ()
     "Save the modes present in `default-modes' and not present in current modes as :excluded,
  
positive.code:                    :name (first mode)
                     :arguments (rest mode))))
  
  (declaim (ftype (function (list (or auto-mode null))
                            (or (cons mode-invocation *) null))
                  rememberable-of))
  (defun rememberable-of (modes auto-mode)
    "Filter MODES based on rememberability by AUTO-MODE."
    (if auto-mode
        (set-difference (mapcar #'mode-invocation modes)
                        (non-rememberable-modes auto-mode)
                        :test #'equals)
        modes))
  
negative.code:       (setf url (url url)))
      (add-modes-to-auto-mode-rules
       (url-infer-match url)
       :include (set-difference (mode-invocations (modes (current-buffer)))
                                (mode-invocations (default-modes (current-buffer)))
                                :test #'equals)
       :exclude (set-difference (mode-invocations (default-modes (current-buffer)))
                                (mode-invocations (modes (current-buffer)))
                                :test #'equals))))
  
  (define-command save-exact-modes-for-future-visits ()
  