Producer with slow consumer

asyncio_producer_consumer.py

import aiohttp
import asyncio

async def l(event, q):
    while True:
        # ok, I'm ready
        event.set()
        # get value to process
        a = await q.get()
        # process it
        await asyncio.sleep(2)
        print(a)


async def m(event, q):
    i = 1
    while True:
        await asyncio.sleep(0.5)
        # pass element to consumer, when it's ready
        if event.is_set():
            await q.put(i)
            event.clear()
        # produce value
        i += 1


el = asyncio.get_event_loop()
ev = asyncio.Event()
qu = asyncio.Queue(5)
tasks = [
            asyncio.ensure_future(l(ev, qu)),
            asyncio.ensure_future(m(ev, qu))
        ]
el.run_until_complete(asyncio.gather(*tasks))
loop.close()

It work's because of await asyncio.sleep() call.