anchor.diff:  
   (defun save-last-active-modes (auto-mode url)
     (when (can-save-last-active-modes auto-mode url)
  -    (setf (last-active-modes auto-mode) (mapcar #'mode-invocation (modes (buffer auto-mode)))
  +    (setf (last-active-modes auto-mode) (mode-invocations (modes (buffer auto-mode)))
             (last-active-modes-url auto-mode) url)))
   
   (defun reapply-last-active-modes (auto-mode)
     (disable-modes
      (mapcar #'name
  -           (set-difference (mapcar #'mode-invocation (modes (buffer auto-mode)))
  +           (set-difference (mode-invocations (modes (buffer auto-mode)))
                              (last-active-modes auto-mode)
                              :test #'equals))
      (buffer auto-mode))
     (enable-modes
      (mapcar #'name
              (set-difference (last-active-modes auto-mode)
  -                           (mapcar #'mode-invocation (modes (buffer auto-mode)))
  +                           (mode-invocations (modes (buffer auto-mode)))
                              :test #'equals))
      (buffer auto-mode)))
   
  
positive.code:     (let ((rules (read stream)))
        (mapcar #'(lambda (rule)
                    (let ((rule (append '(:test) rule)))
                      (setf (getf rule :included) (mapcar #'mode-invocation (getf rule :included))
                            (getf rule :excluded) (mapcar #'mode-invocation (getf rule :excluded)))
                      (when (stringp (getf rule :test))
                        (setf (getf rule :test) `(match-url ,(getf rule :test))))
                      (apply #'make-instance 'auto-mode-rule rule)))
  
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 ()
  