input: Write a function to detect the first vowel in a given string. If the given string contains no vowels, then return None. The function should be case-insensitive and should return the first vowel found or None if no vowels are found.
  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("bcdfg")==None
  assert vowelCheck("AEIOU")=='A'
  assert vowelCheck("")==None
  assert vowelCheck("bcdfg HI")=='I'
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