anchor.diff:               ((not res)
                 (when pres
                   (incf (buffer-undo-node buffer))
  -                (queue:enqueue (buffer-undo-stack buffer) :separator)
  +                (push :separator (buffer-undo-stack buffer))
                   (buffer-undo-modified buffer))
                 pres))))
   
  
positive.code:     (setf (buffer-keep-binfo buffer) nil)
      (setf (buffer-nlines buffer) 1)
      (setf (buffer-undo-size buffer) 0)
      (setf (buffer-undo-stack buffer)
            (if (buffer-enable-undo-p buffer)
                (queue:make-queue *undo-limit*)
                nil))
      (setf (buffer-redo-stack buffer) nil)
      (setf (buffer-undo-node buffer) 0)
      (setf (buffer-saved-node buffer) 0)
  
negative.code:     (setf (buffer-mark-col buffer) 0)
      (setf (buffer-nlines buffer) 1)
      (setf (buffer-undo-size buffer) 0)
      (setf (buffer-undo-stack buffer) nil)
      (setf (buffer-redo-stack buffer) nil)
      (setf (buffer-undo-node buffer) 0)
      (setf (buffer-saved-node buffer) 0)
  