from time import sleep
import multiprocessing
import sys

n = 20
if (len(sys.argv) > 1) :
        n = int (sys.argv[1])
        
# a function that blocks for a moment
def task():
    res = [i for i in range(n)]
    toMain.put(res)
    print("task done!")

toMain = multiprocessing.Queue()

# create a process
p = multiprocessing.Process(target=task)
# run the process
p.start()
p.join()
print("Main thread done")