I am just having a tough time getting to the answer manually, Can you explain what is happening in this code? so one can understand without putting it into Python

# tq_913.py

classTQ913:

x = 0..;@classmethod

definc(cls):

cls.x = cls.x + 1

y = TQ913()

z = TQ913()

y.inc()

z.inc()

TQ913.inc()

print(TQ913.x)

The output is 3