Question: 
Write a python function to find common divisor between two numbers in a given pair.


Model's Code:
def num_comm_div(a, b):
    def gcd(x, y):
        while y:
            x, y = y, x % y
        return x
    return gcd(a, b)



Sample Correct Code:
def ngcd(x,y):
    i=1
    while(i<=x and i<=y):
        if(x%i==0 and y%i == 0):
            gcd=i;
        i+=1
    return gcd;
def num_comm_div(x,y):
  n = ngcd(x,y)
  result = 0
  z = int(n**0.5)
  i = 1
  while(i <= z):
    if(n % i == 0):
      result += 2 
      if(i == n/i):
        result-=1
    i+=1
  return result


Asserts:
assert num_comm_div(2,4) == 2
assert num_comm_div(2,8) == 2
assert num_comm_div(12,24) == 6


Tests:
Test 1 of 3: PASS
Test 2 of 3: PASS
Test 3 of 3: FAIL: AssertionError()

Test 501 of 974: 369/501 (73.65269461077844%): failed