> Would it be possible to add an open() function to the bz2 module?

Yes, it would be quite trivial, though I don't think it would be worthwhile -
all it would do is provide a direct alias for the BZ2File constructor. But as
Antoine said, that is a topic for a separate issue.

@Antoine:

Regarding the use of PY_SSIZE_T_CLEAN, I assume that Py_ssize_t is to be
preferred over plain ssize_t. Is this correct?

Also, I was wondering whether I need to add some sort of license boilerplate to
the beginning of bz2.py? With _bz2module.c, I presume I should retain the
copyright information from the old bz2module.c. Would something like this be ok?

   /* _bz2 - Low-level Python interface to libbzip2.
    *
    * Copyright (c) 2011  Nadeem Vawda <nadeem.vawda@gmail.com>
    *
    * Based on bz2module.c:
    *
    * Copyright (c) 2002  Gustavo Niemeyer <niemeyer@conectiva.com>
    * Copyright (c) 2002  Python Software Foundation; All Rights Reserved
    */

(Browsing through the source files in Lib/ and Modules/, there doesn't seem to
be a clear convention for this sort of thing...)