#!/usr/bin/env python3

import concurrent.futures
import time

def work():
	time.sleep(1)
	return 1

with concurrent.futures.ThreadPoolExecutor(max_workers=1) as e:
	f = e.submit(work)
	for cf in concurrent.futures.as_completed([f,f]):
	#done, notdone = concurrent.futures.wait([f,f], 
	#	return_when=concurrent.futures.ALL_COMPLETED)
	#for cf in done:
		print (cf.result())