[$] Native Python support for units?

Back in April, there was an interesting discussion on the python-ideasmailing list that started as a query about adding support for customliterals, a la C++, but branched off from there. Custom literals arefrequently used for handling units and unit conversion in C++, so thePython discussion fairly quickly focused on that use case. While ideas about apossible feature were batted about, it does not seem like anything that isbeing pursued in earnest, at least at this point. But some of the facetsof the problem are, perhaps surprisingly, more complex than might be guessed.