input: Write a function that takes a string as input and detects the first vowel present in it. If no vowel is found, 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("Hll Wrld")==None
  assert vowelCheck("")==None
  assert vowelCheck("AEIOU")=='A'
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