def find_all(s, t):
  """Returns one-based start position of all occurrences of t in s."""
  offset = 0
  starts = []
  start = s.find(t, offset)
  while start != -1:
    starts.append(start + 1)  # Uses one-based indexing, as Pfam does.
    offset = start + 1
    start = s.find(t, offset)
  return starts