async def gen():
    await asyncio.sleep(0.1)
    v = yield 42
    print(v)
    await asyncio.sleep(0.2)

g = gen()

await g.asend(None)      # Will return 42 after sleeping
                         # for 0.1 seconds.

await g.asend('hello')   # Will print 'hello' and
                         # raise StopAsyncIteration
                         # (after sleeping for 0.2 seconds.)