From http://docs.python.org/3.4/library/asyncio-task.html#example-future-with-run-until-complete

there is an example code:
import asyncio

@asyncio.coroutine
def slow_operation(future):
    yield from asyncio.sleep(1)
    future.set_result('Future in done!')

def got_result(future):
    print(future.result())
    loop.stop()

loop = asyncio.get_event_loop()
future = asyncio.Future()
asyncio.Task(slow_operation(future))
future.add_done_callback(got_result)
loop.run_forever()


I got this:
ethan@amiau:~/Documents/code/python/cpython3.4$ ./python /tmp/demo.py
Future in done!
sys:1: ResourceWarning: unclosed <socket object at 0x7feb49df1058>
sys:1: ResourceWarning: unclosed <socket object at 0x7feb493b48c8>

Here is the patch to shut off the resource warning.

The patch also fixed some typos.

s/Future in done/Future is done/

New changeset ea4c74cc4da5 by Victor Stinner in branch 'default':
Close #20652: asyncio doc: close the event loop in run_forever() example. Fix
http://hg.python.org/cpython/rev/ea4c74cc4da5

New changeset 36005fe2ab9b by Victor Stinner in branch '3.4':
Close #20652: asyncio doc: close the event loop in run_forever() example. Fix
http://hg.python.org/cpython/rev/36005fe2ab9b