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*Please post the tests to this patch and close the other patch.

*Add a documentation patch to this patch

*Let's drop the addition of window().  The C code for it is less 
than beautiful and offers only a minimal performance gain 
over the pure python equivalent.  I've added the pure python 
version to the docs so folks can cut and paste it if they need 
it.  Sorry for the wild goose chase (I had expected the C 
version to be much cleaner and faster and that the python 
verions would've been harder -- actual code was needed for 
me to see it).

* In roundrobin_next(), replace the % operator with:
       if (lz->iternum==lz->itersize) lz-iternum=0;

* In roundrobin_next(), remove the extra blank line 
following "long listsize;"

* Fixup the indentation, currently it is a mix of spaces and 
tabs.  It should be just pure tabs.

* Replace the variable name 'lz' with 'rr'.   I should have
changed that in other places too but for new code it 
should be fixed.

* 'unti' is mispelled in the docstring.