Attached is a proposed patch for the 3.4 branch.

The same modifications are made in this patch as in the patch for the 2.7 branch, with two minor tweaks:
1) The affirmative tone example uses Pool in a with statement as is supported since 3.3.
2) References in the added/moved text are properly resolving (in Sphinx) to the class definition for Pool.


This patch should also work against the 3.3 branch (though should not be applied to 3.2 as the context manager behavior had not yet been added to Pool in 3.2 -- the example in the intro would need changing for this to be applied to 3.2 is all).