PEP 417: Including mock in the Standard Library
http://www.python.org/dev/peps/pep-0417/

Tasks:

* Add mock with tests
* Cleanup mock code to remove Python 2 compatibility
* Add documentation

I'll close this issue when all the tasks are complete.

I’ve seen some things to clean up in the code, like the fact that callable is back in 3.2+, or (I hate to point this) the ugly-according-to-PEP-8 klass instead of cls; I may read the code more carefully later if it helps.

Feel free to suggest changes on this issue. 

_callable can probably go now I agree. 
cls is only suggested by PEP 8 for classmethods I believe, and off the top of my head I don't think mock has any of those.

“If your public attribute name collides with a reserved keyword, append a single trailing underscore to your attribute name.  This is preferable to an abbreviation or corrupted spelling.  (However, notwithstanding this rule, 'cls' is the preferred spelling for any variable or argument which is known to be a class, especially the first argument to a class method.)”

Interesting. As I have to keep the external version of mock in sync with unittest.mock, and I have more important things to do first (like the docs) it would be a gratuitous change for no benefit.

If you have any more substantive suggestions for code cleanup then feel free to suggest them.

unittest.mock addition is complete.