How can I await inside future-like object's __await__?

Question

PEP 0492 adds new __await__ magic method. Object that implements this method becomes future-like object and can be awaited using await. It

Answer 1

I didn't understand why I can't yield from native coroutine inside __await__, but looks like it's possible to yield from generator coroutine inside __await__ and yield from native coroutine inside that generator coroutine. It works:

async def new_sleep():
    await asyncio.sleep(2)

class Waiting:
    def __await__(self):
        @asyncio.coroutine
        def wrapper(coro):
            return (yield from coro)
        return (yield from wrapper(new_sleep()))