Formerly, underlying queue was implemented in terms of two lists. The
new queue is a series of singly-linked fixed length lists.
The new implementation runs much faster, supports multi-way tees, and
allows tees of tees without additional memory costs.
The root ideas for this structure were contributed by Andrew Koenig
and Guido van Rossum.
It works like the pure python verion except:
* it stops storing data after of the iterators gets deallocated
* the data queue is implemented with two stacks instead of one dictionary.
* Updated comment on design of imap()
* Added untraversed object in izip() structure
* Replaced the pairwise() example with a more general window() example
* Removed the ifilter flag wart by splitting it into two simpler functions.
* Fixed comment tabbing in C code.
* Factored module start-up code into a loop.
Documentation:
* Re-wrote introduction.
* Addede examples for quantifiers.
* Simplified python equivalent for islice().
* Documented split of ifilter().
Sets.py:
* Replace old ifilter() usage with new.
* Fixed typo in exception message for times()
* Filled in missing times_traverse()
* Document reasons that imap() did not adopt a None fill-in feature
* Document that count(sys.maxint) will wrap-around on overflow
* Add overflow test to islice()
* Check that starmap()'s argument returns a tuple
* Verify that imap()'s tuple re-use is safe
* Make a similar tuple re-use (with safety check) for izip()
Raymond Hettinger
Guido van Rossum
Michael W. Hudson