measure changes in code python code example

Example: python timer

import time
import os

a = int(0)
b = int(0)

while True:
    print(str(b) + " minutes " + str(a) + " seconds")
    a += 1
    time.sleep(0.9999999)
    if a == 59:
        a = 0
        b += 1
    os.system('cls')