input: from typing import List
  
  
  def findGCD(a: int, b: int) -> int:
      """
      Given two integers a and b, this function finds their GCD using the Euclidean algorithm. 
      
      >>> findGCD(1000, 500)
      500
      >>> findGCD(60, 48)
      12
      """
      if (b == 0): 
          return a
      return findGCD(b, a % b)
output:     while b != 0:
          a, b = b, a % b
      return a