For the record, I am personally +1 on the idea (otherwise I wouldn't

have put so much thought into it over the years). It's just a *lot*
harder to define complete and consistent semantics for the concept
than people often realise.

However, having the question come up twice within the last month
finally inspired me to write the current status of the topic down in a
deferred PEP: http://www.python.org/dev/peps/pep-3150/