Not backported because of behaviour change.

added test script and expected output file as well
this closes patch 103297.
__all__ attributes will be added to other modules without first submitting
a patch, just adding the necessary line to the test script to verify
more-or-less correct implementation.

Use != instead of <> since <> is documented as "obsolescent".
Use "is" and "is not" when comparing with None or type objects.

*this* set of patches is Ka-Ping's final sweep:

The attached patches update the standard library so that all modules
have docstrings beginning with one-line summaries.

A new docstring was added to formatter.  The docstring for os.py
was updated to mention nt, os2, ce in addition to posix, dos, mac.

    1. Comments at the beginning of the module, before
       functions, and before classes have been turned
       into docstrings.

    2. Tabs are normalized to four spaces.

Also, removed the "remove" function from dircmp.py, which reimplements
list.remove() (it must have been very old).