input: Write a function to find the GCD of two numbers. The function should use the Euclidean algorithm and return the GCD. If any of the numbers is zero, the GCD should be returned as zero.
  
  assert findGCD(1000, 500)==500
  assert findGCD(14, 21)==7
  assert findGCD(0, 0)==0
  assert findGCD(123456, 654321)==3
output: def findGCD(a, b):
      if a == 0 or b == 0:
          return 0
      while b != 0:
          a, b = b, a % b
      return a