input: Write a python function to count number of vowels in the string.
  assert Check_Vow('corner','AaEeIiOoUu') == 2
  assert Check_Vow('valid','AaEeIiOoUu') == 2
  assert Check_Vow('true','AaEeIiOoUu') ==2
  
output: def Check_Vow(string, vowels):
      return sum(1 for char in string if char in vowels)