input: Write a function to find the GCD of two numbers using the Euclidean algorithm. If either of the numbers is zero, return the other number as the GCD. The function should take two integers as input and return an integer representing the GCD.
  def findGCD(a, b): 
     if (b == 0): 
         return a
     return findGCD(b, a % b)
  assert findGCD(1000, 500) == 500
  assert findGCD(48, 18) == 6
  assert findGCD(0, 5) == 5
  assert findGCD(35, 0) == 35
  assert findGCD(12, 15) == 3
output: def findGCD(a, b): 
     if (b == 0): 
         return a
     return findGCD(b, a % b)