from concurrent.futures import ThreadPoolExecutor

import time

pool = ThreadPoolExecutor(max_workers=8)

def func(x, y):

    time.sleep(5)

    return x, y

def do_func(x, y):

    result = yield pool.submit(func, x, y)

    print('Got: ', result)

 

def after(delay, gen):

    yield pool.submit(time.sleep, delay)

    result = None

    try:

        while True:

            f = gen.send(result)

            result = yield f

    except StopIteration:

        print('after ecoutnered StopIteration.')

 

class Task:

    def __init__(self, gen):

        self._gen = gen

    def step(self, value=None):

        # Run to the next yield

        try:

            fut = self._gen.send(value)

            # Future returned

            fut.add_done_callback(self._wakeup)

        except StopIteration as exc:

            print('Task encountered StopIteration.')

    def _wakeup(self, fut):

        # handler for results

        result = fut.result()

        self.step(result)  # Feedback loop (run to next yield)