I agree that the lxml API is somewhat clumsy here. I just mentioned it to show that there are already ways to do it in a backwards compatible way, so this change does two things: it breaks existing code, and it does so in a way that is incompatible with other existing implementations. That's what *I* would call horrible.

Also, this is absolutely not a feature that is restricted to Py3, so what's the equivalent feature in the standard library of Py2 going to be, and how much code will it break for the Py2 series?