sage-mode does not work

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System information

64-bit Linux OS
GNU Emacs 24.1.1 (x86_64-unknown-linux-gnu, X toolkit, Xaw scroll bars) of 2012-06-25
sage-mode-0.7

Installation

On sage-mode project page it is said that sage-mode should be installed with the following command:

sage -f sage-mode-0.7.spkg

This does not work though sage-mode-0.6.spkg can be installed this way without any problems.

In order to install this package I had to download it manually. Here is the correct installation command:

sage -f ~/Downloads/sage-mode-0.7.spkg

I have put the following code into my emacs.el:

(add-to-list 'load-path (expand-file-name
                         "/home/maksim/Applications/sage/data/emacs"))
(require 'sage "sage")
(setq sage-command "/home/maksim/Applications/sage/sage")

Syntax highlighting

Running M-x sage-mode in Emacs leads to the following error message:

Symbol's value as variable is void: python-source-modes

though package python is a built-in one and works well.

In order to avoid this problem I have added the following code:

(setq python-source-modes 'python-mode)

This made sage-mode work properly (at least syntax highlighting).

run-sage

run-sage command does not work. It reports

Symbol's value as variable is void: sage-buffer

Setting this variable to nil does not help:

Symbol's function definition is void: python-args-to-list

The file .../lisp/progmodes/python.el in the Emacs distribution does contain this function.