anchor.diff:  
   (defclass input-hint (hint) ())
   
  +(defclass textarea-hint (hint) ())
  +
   (defmethod object-string ((link-hint link-hint))
     (url link-hint))
   
  
positive.code:                         ((equal "input" object-type)
                           (make-instance 'input-hint
                                          :identifier (cdr (assoc :identifier element))
                                          :hint (cdr (assoc :hint element))))))))
  
  (defclass hint ()
  
negative.code:   (click-button :buffer (current-buffer) :next-identifier (identifier button-hint)))
  
  (defmethod %follow-hint ((input-hint input-hint))
    (focus-element :buffer (current-buffer) :next-identifier (identifier input-hint)))
  
  (defmethod %follow-hint ((textarea-hint textarea-hint))
    (focus-element :buffer (current-buffer) :next-identifier (identifier textarea-hint)))
  
  (defmethod %follow-hint-new-buffer-focus ((link-hint link-hint))
    (let ((new-buffer (make-buffer)))
  