anchor.diff:              :type htree:history-tree
               :initarg :history
               :initform (htree:make))
  +   (history-blacklist :accessor history-blacklist
  +                      :type list-of-strings
  +                      :initarg :history-blacklist
  +                      ;; TODO: Find a more automated way to do it.  WebKitGTK
  +                      ;; automatically removes such redirections from its
  +                      ;; history.  How?
  +                      :initform '("https://duckduckgo.com/l/")
  +                      :documentation "URI prefixes to not save in history.
  +Example: DuckDuckGo redirections should be ignored or else going backward in
  +history after consulting a result reloads the result, not the duckduckgo
  +search.")
      (keymap-scheme
       :initform
       (define-scheme "web"
  
positive.code:     (copy-to-clipboard input)))
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;; Warning: To specialize `on-signal-load-committed' we must be in the right package.
  (in-package :next)
  (defmethod on-signal-load-committed ((mode next/web-mode::web-mode) url)
    nil)
  
negative.code:     (unzoom-page :buffer buffer)
      (set-window-title (current-window) buffer)
      (print-status)
  
      (unless (find-if (alex:rcurry #'str:starts-with? url)
                       (next/web-mode:history-blacklist mode))
        (htree:add-child (make-instance 'buffer-description
                                        :url url
                                        :title (title buffer))
                         (next/web-mode::history mode)
                         :test #'equals)
        (when url
          (history-add url :title (title buffer))))
  
      (match (session-store-function *browser*)
        ((guard f f) (funcall-safely f))))
    (echo "Finished loading: ~a." url)
  