I don't really think much more needs to be done other than agree on this tracker issue that it's something we want, and that Ethan's implementation is good enough.  It's been a while since I looked that the code but it seemed good to me before, so if Ethan is happy with it going into the stdlib, so am I.  As for the feature, it *is* a little magical, but not so much that it would be confusing or ambiguous, so I'm +1 on it.

I'll defer to Ethan for the final decision, but if we have tests and documentation, I'd be very happy to see this in 3.6.