Question: 
Write a python function to count unset bits of a given number.


Model's Code:
def count_unset_bits(n):
    total_bits = n.bit_length()
    unset_bits = total_bits - bin(n).count('1')
    return unset_bits



Sample Correct Code:
def count_unset_bits(n): 
    count = 0
    x = 1
    while(x < n + 1): 
        if ((x & n) == 0): 
            count += 1
        x = x << 1
    return count  


Asserts:
assert count_unset_bits(2) == 1
assert count_unset_bits(4) == 2
assert count_unset_bits(6) == 1


Tests:
Test 1 of 3: PASS
Test 2 of 3: PASS
Test 3 of 3: PASS

Test 331 of 974: 238/331 (71.90332326283988%): success