input: Write a function to detect the first vowel in a given string. If the string contains no vowels, the function should return None.
  def vowelCheck(inputString): 
      vowels = ['a','e','i','o','u','A','E','I','O','U'] 
      for x in inputString: 
          if x in vowels: 
              return x
  assert vowelCheck("Hello World") == 'e'
  assert vowelCheck("Python") == 'o'
  assert vowelCheck("Cry") == None
  assert vowelCheck("AI") == 'I'
  assert vowelCheck("") == None
output: def vowelCheck(inputString): 
      vowels = ['a','e','i','o','u','A','E','I','O','U'] 
      for x in inputString: 
          if x in vowels: 
              return x