power TypeErrors

[Tim Peters]

[Michael Hudson]
> ...
> It's a bit odd that there's no cmath.pow().

But not surprising:  a good-quality pow() is difficult to code even for
reals, and numerical analysts had nothing to do with Python's cmath.  If
"most" vendors bother to implement C99 (I'm afraid that's not a certainty),
Python can borrow its cpow() to plug this hole.  Short of that,
exp(y*log(x)) makes users responsible for their own numeric screwups.