Documentation idea

Background
----------
In the itertools module docs, I included pure python equivalents for each of the C functions.  Necessarily,
some of those 
equivalents are only approximate but they seem to have greatly enhanced the docs.  Something similar is in
the builtin docs for 
any() and all().  The new collections.namedtuple() factory function also includes a verbose option that
prints a pure python 
equivalent for the generated class. And in the decimal module, I took examples directly from the spec and
included them in 
doc-testable docstrings.  This assured compliance with the spec while providing clear examples to anyone
who bothers to look at the 
docstrings.

For itertools docs, I combined those best practices and included sample calls in the pure-python code (see
the current docs for 
itertools to see what I mean -- perhaps look at the docs for a new tool like itertools.product() or
itertools.izip_longest() to see 
how useful it is).

Bright idea
----------
Let's go one step further and do this just about everywhere and instead of putting it in the docs, attach an
exec-able string as an 
attribute to our C functions.  Further, those pure python examples should include doctests so that the user
can see a typical 
invocation and calling pattern.

Say we decide to call the attribute something like ".python", then you could write something like: