pub fn clear(&mut self) {
        self.in_progress_queue.clear();
        self.queued_outputs.clear();
        self.next_incoming_index = 0;
        self.next_outgoing_index = 0;
    }
Clear the whole `FuturesOrdered` queue.

This function clears the pending futures and the queued outputs
to make it fully empty.
futures-util/src/stream/futures_ordered.rs