Example using asyncio of Python 3

asyncio_example.py

# def xx(num):
#     n = 0
#     while n < num:
#         yield n
#         print(n)
#         n += 1

# x = xx(12)
# for i in x:
#     print("asd", i)

import asyncio
import datetime

def main1():
    @asyncio.coroutine
    def hello_world():
        print("hello_world")
        yield from asyncio.sleep(0.1)

    @asyncio.coroutine
    def display_date(loop):
        end_time = loop.time() + 1.0
        while True:
            print(datetime.datetime.now(), loop.time(), end_time)
            if loop.time() >= end_time:
                break
            yield from asyncio.wait_for(hello_world(), 1.0)


    loop = asyncio.get_event_loop()
    loop.run_until_complete(display_date(loop))
    loop.close()

def main2():
    @asyncio.coroutine
    def slow_op(future, loop):
        yield from asyncio.sleep(1)
        future.set_result('Done with slow_op')
        print("Completed slow_op")
        loop.stop()

    loop = asyncio.get_event_loop()
    future = asyncio.Future()
    asyncio.async(slow_op(future, loop))
    print("Should print before slow_op")
    loop.run_forever()
    loop.close()

if __name__ == '__main__':
    main2()