import time
from threading import Thread


def worker(num: int) -> None:
    print("Поток {} работает".format(num))
    time.sleep(5)
    print("Поток {} - закончил работу".format(num))


threads: list[Thread] = []
for i in range(1, 4):
    th = Thread(target=worker, args=(i,))
    threads.append(th)
    th.start()

for theard in threads:
    theard.join()