single-thread-eg-0.py

from threading import Thread
from time import perf_counter


def sum_up_to(start: int, end: int):
    total = 0
    print('start...')
    for i in range(start, end):
        total += i
    print('end...')

    print(f'sum from {start}..{end} is {total}.')

if __name__ == "__main__":
    start = perf_counter()
    t1 = Thread(target=sum_up_to, args=(1, 10_000))
    t1.start()
    t1.join()
    print(f'Took {perf_counter() - start:.6f} seconds.')