There's no reason that `count('', 'a')` for `'', 'a', 'aa', ...` or `count((), (1,))` for `(), (1,), (1, 1), ...` shouldn't work.

count(a, b) should be equivalent to accumulate(chain((a,), repeat(b)))

The docs don't strongly suggest that it won't work (it says *start* is a number, but the "roughly equivalent to" generator would work for str/tuple/etc)