anchor.diff:      (setf (buffer-mark-linum buffer) 1)
       (setf (buffer-mark-col buffer) 0)
       (setf (buffer-nlines buffer) 1)
  -    (setf (buffer-undo-stack buffer) nil)
  +    (setf (buffer-undo-stack buffer) (make-tlist))
       (setf (buffer-redo-stack buffer) nil)
       (push buffer *buffer-list*)
       buffer))
  
positive.code:     (setf (buffer-cache-linum buffer) 1)
      (setf (buffer-keep-binfo buffer) nil)
      (setf (buffer-nlines buffer) 1)
      (setf (buffer-undo-stack buffer) nil)
      (setf (buffer-redo-stack buffer) nil)))
  
  (defun buffer-check-marked (buffer)
  
negative.code:     (buffer-filename buffer)))
  
  (defun push-undo-stack (buffer elt)
    (tlist-add-right (buffer-undo-stack buffer) elt))
  
  (defun push-redo-stack (buffer elt)
    (push elt (buffer-redo-stack buffer)))
  