def multi_find(s: str, f: str):
	"""Finds every occurrence of substring F in string S.
	Returns a list of indexes where each occurence starts."""
	res = []
	scanned = 0
	while len(s) > 0:
		found = s.find(f)
		if found == -1: break

		res.append(found + scanned)
		s = s[found + 1:]
		scanned += found + 1
	return res