run callback on stop loop

example.py

import asyncio

async def main():
    print('start')

    async def on_stop():
        try:
            await asyncio.sleep(10**10)
        except asyncio.CancelledError:
            pass
        print('stopping start')
        await asyncio.sleep(1)
        print('stopping end')
    asyncio.ensure_future(on_stop())

    await asyncio.sleep(1)

asyncio.run(main())