Buggy python submission (verdict: Runtime Error):
# coding: utf-8
import os
from sys import stdin, stdout

__LOCAL__ = True
if(__LOCAL__):
    __dirname = os.path.dirname(__file__)
    __basename = os.path.splitext(os.path.basename(__file__))[0]
    __inputname = './input/' + __basename + '.txt'
    __outputname = './output/' + __basename + '.txt'
    input_path = os.path.join(__dirname, __inputname)
    output_path = os.path.join(__dirname, __outputname)
    stdin = open(input_path)
    stdout = open(output_path, "w")

def TLEmain():
    A, B = map(int,stdin.readline().rstrip().split(' '))
    ans = 0
    for x in range(A,B+1):
        ans ^= x
    print(ans)

def xorsum(A):
    if(A&1):
        return (A+1)//2 & 1
    else:
        return ((A+1)//2 & 1) ^ A

def main():
    A, B = map(int,stdin.readline().rstrip().split(' '))
    if(A==B):
        ans = A
        stdout.write("{}\n".format(ans))
    else:
        ans = xorsum(A-1)^xorsum(B)
        stdout.write("{}\n".format(ans))     

if __name__ == "__main__":
    main()
    

Fixed submission:
# coding: utf-8
import os
from sys import stdin, stdout

__LOCAL__ = False
if(__LOCAL__):
    __dirname = os.path.dirname(__file__)
    __basename = os.path.splitext(os.path.basename(__file__))[0]
    __inputname = './input/' + __basename + '.txt'
    __outputname = './output/' + __basename + '.txt'
    input_path = os.path.join(__dirname, __inputname)
    output_path = os.path.join(__dirname, __outputname)
    stdin = open(input_path)
    stdout = open(output_path, "w")

def TLEmain():
    A, B = map(int,stdin.readline().rstrip().split(' '))
    ans = 0
    for x in range(A,B+1):
        ans ^= x
    print(ans)

def xorsum(A):
    if(A&1):
        return (A+1)//2 & 1
    else:
        return ((A+1)//2 & 1) ^ A

def main():
    A, B = map(int,stdin.readline().rstrip().split(' '))
    if(A==B):
        ans = A
        stdout.write("{}\n".format(ans))
    else:
        ans = xorsum(A-1)^xorsum(B)
        stdout.write("{}\n".format(ans))     

if __name__ == "__main__":
    main()

Buggy python submission (verdict: Time Limit Exceeded):
# coding: utf-8
import os
from sys import stdin
from functools import total_ordering

# __dirname = os.path.dirname(__file__)
# __basename = os.path.splitext(os.path.basename(__file__))[0]
# __targetname = './input/' + __basename + '.txt'
# target_path = os.path.join(__dirname, __targetname)
# stdin = open(target_path)


def main():
    A, B = map(int,stdin.readline().rstrip().split(' '))
    ans = 0
    for x in range(A,B+1):
        ans ^= x
    print(ans)

if __name__ == "__main__":
    main()
    

Fixed submission:
# coding: utf-8
import os
from sys import stdin, stdout

__LOCAL__ = False
if(__LOCAL__):
    __dirname = os.path.dirname(__file__)
    __basename = os.path.splitext(os.path.basename(__file__))[0]
    __inputname = './input/' + __basename + '.txt'
    __outputname = './output/' + __basename + '.txt'
    input_path = os.path.join(__dirname, __inputname)
    output_path = os.path.join(__dirname, __outputname)
    stdin = open(input_path)
    stdout = open(output_path, "w")

def TLEmain():
    A, B = map(int,stdin.readline().rstrip().split(' '))
    ans = 0
    for x in range(A,B+1):
        ans ^= x
    print(ans)

def xorsum(A):
    if(A&1):
        return (A+1)//2 & 1
    else:
        return ((A+1)//2 & 1) ^ A

def main():
    A, B = map(int,stdin.readline().rstrip().split(' '))
    if(A==B):
        ans = A
        stdout.write("{}\n".format(ans))
    else:
        ans = xorsum(A-1)^xorsum(B)
        stdout.write("{}\n".format(ans))     

if __name__ == "__main__":
    main()