N = 10 ** 7

async def agen():
    for i in range(N):
        yield i

class AIter:
    def __init__(self):
        self.i = 0

    def __aiter__(self):
        return self

    async def __anext__(self):
        i = self.i
        if i >= N:
            raise StopAsyncIteration
        self.i += 1
        return i