human: 整理以下代码。 输入：
def count_vowel(str):
  vowels=['a','e','i','o','u']
  cnt=0
  for alph in str:
    if alph in vowels:
        cnt+=1
return cnt
 bot: def count_vowel(str):
  vowels=['a','e','i','o','u']
  cnt=0
  for alph in str:
    if alph in vowels:
        cnt+=1

  return cnt