async def METHOD_NAME(self, delay: float | None = None) -> None:
    """Insert a pause.
    Args:
        delay: Seconds to pause, or None to wait for cpu idle.
    """
    # These sleep zeros, are to force asyncio to give up a time-slice.
    await self._wait_for_screen()
    if delay is None:
        await wait_for_idle(0)
    else:
        await asyncio.sleep(delay)
    self.app.screen._on_timer_update()