Helper functions
A helper function performs part of the computation of another function. It allows you to reuse common code without repeating yourself. For instance, suppose you had a few lines of code that printed out the elapsed time at various points in a function, as follows:
import time
def do_things():
    start_time = time.perf_counter()
    for i in range(10):
        y = i ** 100
        print(time.perf_counter() - start_time, "seconds elapsed")
    x = 10**2
    print(time.perf_counter() - start_time, "seconds elapsed")
    return x
do_things()
The output is as follows:
Figure 3.21 – Timing our helper functions
The print statement is repeated twice in the preceding code, and would be better expressed as a helper function, as follows:
import...
