input: Write a function to find the GCD of two numbers using the Euclidean algorithm. If the second number is 0, return the first number. Otherwise, recursively call the function with the second number and the remainder of the division of the first number by the second number.
  
  
  def findGCD(a, b): 
     if (b == 0): 
         return a
     return findGCD(b, a % b)
  
  
  assert findGCD(1000, 500) == 500
  assert findGCD(20, 8) == 4
  assert findGCD(7, 3) == 1
  assert findGCD(9, 0) == 9
  assert findGCD(0, 0) == 0
output: def findGCD(a, b): 
     if (b == 0): 
         return a
     return findGCD(b, a % b)