<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 async def anext(self):
 """Fetch the next value from the iterable."""

        try:
            f = next(self._iter)
        except StopIteration as exc:
            raise StopAsyncIteration() from exc
        return await f