It turns out in Python there's no generator version of str.split() (which produces a list of substrings). Some recipes in this Stackoverflow answer, of which I suppose

def split_iter(string):
  return (x.group(0) for x in re.finditer(r"[A-Za-z']+", string))

is "terse enough" (and much more functional, though it requires proper escaping of re-special characters). It's hard not to quip that C has had strtok (or, more reasonably, strtok_r) for a very long time.