Python Workers Checksum Challenge

worker_checksum.py

# Faster XOR
def getXor(a, b):
    return [b, 1, b + 1, 0][b % 4] ^ [(a-1), 1, (a-1) + 1, 0][(a-1) % 4]


def solution(start, length):
    l = length
    cs = 0
    while l > 0:
        cs ^= getXor(start, start + l - 1)
        start = start + length
        l = l - 1
    return cs


print solution(0, 3)  # 2
print solution(17, 4)  # 14