Tim Peter's explanation of 'timsort' in the file
'listsort.txt' is just excellent. 
I would recommend, however, that all occurrences of
'data is' be replaced by 'data are'.

Just a minor nit.

-gyro

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While I agree that 'data are' when 'data' is used in isolation, I can 
see combinations such as 'list data' being equivalent to 'dataset', 
which 'is'.  So I would have to see examples of context to be sure 
I agreed with your recommendation.

In any case, listsort.txt is an optional implementation note and not 
part of the official reference docs (and not accessible that I know 
of via docs.python.org).  Hence, a fix, even if agreed to, would 
have very low priority unless Tim or a doc maven got 'bugged' by 
it.  Are you willing to make a revised file and a diff that would 
verify that only appropriate changes were made?

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Sorry.  Am closing this to eliminate noise from the tracker.
 The grammar nit arguable and inconsequential (because it is
not in the main documentation and is readable as-ias).

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It is a very minor issue, but the change is not arguable
from the perspective of correct English grammar.

If I submit a diff, will it (eventually) be reviewed or applied?

-gyro

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I mentally replaced "data is" by "data are", and disliked how 
it read then.  So, no, I won't apply such a patch.  English 
grammar changes over time to match what careful English 
speakers actually use, so I'll view this is a crusade to stamp 
out effete elitism -- "data are" my ass <wink>.

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Fair enough. I should have known that Mr. Peters would have
considered this already. 

Just-trying-to-make-Python-docs-more-appealing-to-pedants-like-me'ly
yours,
gyro