Actually ... if I were a fan of the "".join() idiom, I'd seriously
propose 0.sum(numeric_iterable) as the RightThang{tm]. Then we could
deprecate "".join(string_iterable) in favor of "".sum(string_iterable)
(with the same efficient semantics).
Actually, there is no need to wait for 0.sum() to propose "".sum...
but it is only a spelling change, so no real benefit.