input: Write a function to detect a vowel in a given string. 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("Brrr!") == None
  assert vowelCheck("Anaconda") == 'A'
  assert vowelCheck("Python") == None
  assert vowelCheck("Eureka") == 'E'
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