Emacs Ipython Notebook で保存できないエラーをなんとかする

save_ein.el

(defun save-buffer (&optional arg)
    (interactive "p")
    (if (eq major-mode 'ein:notebook-multilang-mode)
        (ein:notebook-save-notebook-command)
      (let ((modp (buffer-modified-p))
            (make-backup-files (or (and make-backup-files (not (eq arg 0)))
                                   (memq arg '(16 64)))))
        (and modp (memq arg '(16 64)) (setq buffer-backed-up nil))
        (if (and modp (buffer-file-name))
            (message "Saving file %s..." (buffer-file-name)))
        (basic-save-buffer)
        (and modp (memq arg '(4 64)) (setq buffer-backed-up nil))))

;;; advice /defadvice that fails
(defun save-ein()
    (if (eq major-mode 'ein:notebook-multilang-mode)
      (ein:notebook-save-notebook-command))))
(advice-add 'save-buffer :before #'save-ein)