input: Write a function to detect if a given string contains any vowels. If a vowel is found, return the vowel; otherwise, 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("Fly")==None
  assert vowelCheck("Apple")=='A'
  assert vowelCheck("DRY")==None
  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