On Thu, 11 Feb 2016 at 02:13 Steven D'Aprano <steve@pearwood.info> wrote:
On Wed, Feb 10, 2016 at 08:41:27PM -0800, Andrew Barnert wrote:

> And honestly, are you really claiming that in your opinion, "123_456_"
> is worse than all of their other examples, like "1_23__4"?

Yes I am, because 123_456_ looks like you've forgotten to finish typing
the last group of digits, while 1_23__4 merely looks like you have no
taste.

OK, but the keyword in your sentence is "taste". If we update PEP 8 for our needs to say "Numerical literals should not have multiple underscores in a row or have a trailing underscore" then this is taken care of. We get a dead-simple rule for when underscores can be used, the implementation is simple, and we get to have more tasteful usage in the stdlib w/o forcing our tastes upon everyone or complicating the rules or implementation.