input: Write a function to find the GCD of two numbers using the Euclidean algorithm. The function should take two integers as input and return their GCD. If either number is zero, the function should return the other number as the GCD.
  
  def findGCD(a, b): 
     if (b == 0): 
         return a
     return findGCD(b, a % b)
      
  assert findGCD(1000, 500) == 500
  assert findGCD(7, 3) == 1
  assert findGCD(0, 12) == 12
  assert findGCD(12, 0) == 12
  assert findGCD(0, 0) == 0
output: def findGCD(a, b): 
     if (b == 0): 
         return a
     return findGCD(b, a % b)