Async version of :meth:`timeRange`.

async def timeRangeAsync(
        start: datetime.time, end: datetime.time,
        step: float) -> AsyncIterator[datetime.datetime]:
    """
    Async version of :meth:`timeRange`.
    """
    assert step > 0
    start = _fillDate(start)
    end = _fillDate(end)
    delta = datetime.timedelta(seconds=step)
    t = start
    while t < datetime.datetime.now():
        t += delta
    while t <= end:
        await waitUntilAsync(t)
        yield t
        t += delta