time.clock not functioning

[Oldman45]

I am using the following coding, from a text book, to compare two methods of measuring execution time for coding but time.clock is not recognised. I am on Windows 10 using Python 3.9.2
The coding is:

import time

def do_my_sum(xs):
    sum = 0
    for v in xs:
        sum += v
    return

sz = 10000000   #10000000 elements in the list
testdata = range(sz)

t0 = time.clock()
my_result  =  do_my_sum(testdata)
t1 = time.clock()
print("my_result   = {0} {time taken = {1:4f} seconds) "
          ,format(their_result, t1 - t0))

t2 = time.clock()
their_result = sum(testdata)
t3 = time.clock()
print("their_result = {0} (time taken = {1: .4f} seconds) "
          .format(their_result, t3 - t2))

And the output is:

Output:
Traceback (most recent call last):
  File "C:\Users\qm31\Desktop\testing.py", line 12, in <module>
    t0 = time.clock()
AttributeError: module 'time' has no attribute 'clock'

Please can anyone shed light on why time.clock is not recognised? Thank you.