this patch applies to anonymous CVS as of 2004-08-02 at 07:
54:58 PDT.

it adds O(1) membership testing; for example:

Python 2.4a1+ (#2, Aug  2 2004, 09:11:43) 
[GCC 3.3 20030304 (Apple Computer, Inc. build 1495)] on 
darwin
Type "help", "copyright", "credits" or "license" for more 
information.
>>> import sys
>>> sys.maxint
2147483647
>>> sys.maxint in xrange(sys.maxint)
False

in current CVS, this would take untold hours to complete 
(because Python arrives at this answer by iterating on the 
sequence). this patch adds a __contains__ method to the 
xrange object which examines the xrange's pattern and 
determines the correct answer instantly based on that pattern.