input: Write a function to compute the GCD (Greatest Common Divisor) of two given numbers. The function should take two integers as arguments and return the GCD of these numbers. If either of the numbers is zero, the function should return 0.
  assert findGCD(1000, 500)==500
  assert findGCD(20, 30)==10
  assert findGCD(15, 0)==0
  assert findGCD(0, 0)==0
  assert findGCD(27, 21)==3
output: def findGCD(a, b):
      if a == 0 or b == 0:
          return 0
      while b != 0:
          a, b = b, a % b
      return a