message: Update count-unique-characters-of-all-substrings-of-a-given-string.py
diff: @@ -15,10 +15,10 @@ class Solution(object):
  result = 0
  for i, c in enumerate(S):
  k, j = index[c]
  - result += (i-j) * (j-k)
  + result = (result + (i-j) * (j-k)) % M
  index[c] = [j, i]
  for c in index:
  k, j = index[c]
  - result += (len(S)-j) * (j-k)
  - return result % M
  + result = (result + (len(S)-j) * (j-k)) % M
  + return result
  