anchor.diff:      (values (or (cons mode-invocation *) null) &optional))
   (defun rememberable-of (modes)
     "Filter MODES based on `rememberable-p'."
  -  (mode-invocations (remove-if (complement #'rememberable-p) modes)))
  +  (mode-invocations (sera:filter #'rememberable-p modes)))
   
   (define-class auto-mode-rule ()
     ((test (error "Slot `test' should be set.")
  
positive.code:   (:method ((mode mode-invocation))
      mode)
    (:method ((mode nyxt:root-mode))
      (make-instance 'mode-invocation :name (mode-name mode)))
    (:method ((mode symbol))
      (alex:if-let ((command (nyxt::mode-command mode)))
        (make-instance 'mode-invocation :name (nyxt:name command))
        (echo-warning "Auto-mode rule: unknown mode symbol ~s" mode)))
    (:method ((mode list))
      (check-type mode (cons symbol *))
      (make-instance 'mode-invocation
                     :name (first mode)
                     :arguments (rest mode))))
  
  (defun mode-invocations (mode-list)
    "Return the mode invocations corresponding to mode specifiers in MODE-LIST.
  
negative.code:                            :test #'equals))
     (buffer auto-mode)))
  
  (-> new-page-request-p (request-data) (values boolean &optional))
  (defun new-page-request-p (request-data)
    "Whether the REQUEST-DATA is a request for a new page load.
  Resource/font/ads/anchor loads are safely ignored.
  