input: Write a function to detect the vowel in a given string. If a vowel is found in the string, return the first vowel encountered. If no vowel is found, return None. The function should ignore case and should work for both lowercase and uppercase letters.
  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("Cmptr")==None
  assert vowelCheck("AEIOU")=="A"
  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