anchor.diff:    ((url (quri:uri "")
           :type (or quri:uri string))
      (title "")
  +   (last-access "" ; TODO: Remove with Nyxt 2.0?
  +                :type (or string local-time:timestamp)
  +                :export nil
  +                :documentation "This slot is only kept for backward
  +compatibility to import the old flat history.")
      ;; TODO: For now we never increment the explicit-visits count.  Maybe we
      ;; could use a new buffer slot to signal that the last load came from an
      ;; explicit request?
  
positive.code:           (local-time:format-timestring nil (htree:last-access binding)
                                          :timezone local-time:+utc-zone+))
      (call-next-method new-binding stream serialization-state)))
  
  (defun make-history-tree (&optional (buffer (current-buffer)))
    "Return a new global history tree for `history-entry' data."
  
negative.code:              (echo "Importing deprecated global history of ~a URLs from ~s."
                     (hash-table-count old-history)
                     (expand-path old-path))
               (with-data-access (history path
                                  :default (make-history-tree)) ; TODO: What shall the default owner be here?
                 (maphash (lambda (key data)
                            (declare (ignore key))
                            (let ((last-access (last-access data)))
                              ;; Remove last-access from DATA to avoid storing it
                              ;; twice.
                              (setf (last-access data) "")
                              (htree:add-entry history data last-access)))
                          old-history)))
  
             (%restore ()
               (let* ((path (if (uiop:file-exists-p (expand-path path))
  