fn build_streams_for_mode(
mode: MiningMode,
engine: &Arc<MiningEngine>,
) -> SelectAll<Pin<Box<dyn FusedStream<Item = ()> + Send>>>fn build_streams_for_mode(
mode: MiningMode,
engine: &Arc<MiningEngine>,
) -> SelectAll<Pin<Box<dyn FusedStream<Item = ()> + Send>>>