asyncio.callback

3.py

import time
import asyncio


def q2(val):
    print("delay 1 second")
    time.sleep(1)
    print(val)


def cb(fut):
    r = fut.result()
    print(r, "world")
    fut._loop.stop()

loop = asyncio.get_event_loop()
fut = loop.run_in_executor(None, q2, "hello")
fut.add_done_callback(cb)
loop.run_forever()

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