Find all occurrences of a substring

import re

[m.start() for m in re.finditer('test', 'test test test test')]
# [0, 5, 10, 15]

def findAll(s, idx):
  e = s[0]
  i = s.find(e)
  while i is not -1:
    yield i
    i = s.find(e, i + 1)