input: def findGCD(a: int, b: int) -> int:
      """ Find the greatest common divisor (GCD) of two numbers using the Euclidean algorithm.
      >>> findGCD(1000, 500)
      500
      """
      if (b == 0):
          return a
      return findGCD(b, a % b)
output:     if (b == 0):
          return a
      return findGCD(b, a % b)