anchor.diff:  (defun unbury-buffer (buffer)
     (check-type buffer buffer)
     (unless (buffer-temporary-p buffer)
  -    (setf *buffer-list*
  -          (cons buffer
  -                (delete buffer (buffer-list)))))
  +    (set-buffer-list
  +     (cons buffer
  +           (delete buffer (buffer-list)))))
     buffer)
   
   (defun bury-buffer (buffer)
     "`buffer`をバッファリストの一番最後に移動させ、バッファリストの先頭を返します。"
     (check-type buffer buffer)
     (unless (buffer-temporary-p buffer)
  -    (setf *buffer-list*
  -          (nconc (delete buffer (buffer-list))
  -                 (list buffer))))
  +    (set-buffer-list
  +     (nconc (delete buffer (buffer-list))
  +            (list buffer))))
     (car (buffer-list)))
   
   (defun get-file-buffer (filename)
  
positive.code:   (alexandria:when-let ((hooks (variable-value 'kill-buffer-hook :global)))
      (run-hooks hooks buffer))
    (buffer-free buffer)
    (setf *buffer-list* (delete buffer (buffer-list))))
  
  (defun get-next-buffer (buffer)
    "バッファリスト内にある`buffer`の次のバッファを返します。"
  
negative.code: 
  (defvar *buffer-list* '())
  
  (defun buffer-list ()
    "`buffer`のリストを返します。"
    *buffer-list*)
  
  (defun set-buffer-list (buffer-list)
    (setf *buffer-list* buffer-list))
  
  (defun add-buffer (buffer)
    (check-type buffer buffer)
    (assert (not (get-buffer (buffer-name buffer))))
    (set-buffer-list (cons buffer (buffer-list))))
  
  (defun any-modified-buffer-p ()
    (find-if (lambda (buffer)
  