input: Write a function to find the GCD (Greatest Common Divisor) of two numbers. The function should take two integers as input and return their GCD. Use the Euclidean algorithm for this purpose.
  assert findGCD(10, 4) == 2
  assert findGCD(1000, 500) == 500
  assert findGCD(15, 25) == 5
  assert findGCD(7, 11) == 1
output: def findGCD(a, b):
      while b:
          a, b = b, a % b
      return a