merge.rs

fn merge(merged_result_chan: Sender<PipelineMsg>) -> Sender<PipelineMsg> {
    let (chan, port) = channel();
    let _ = thread::Builder::new().spawn(move || {
        // Iteration will stop when all senders are dropped.
        // This happens when the worker stop their iteration, 
        // and drop their "merge_chan"...
        for msg in port {
            let squared = match msg {
                PipelineMsg::Squared(num) => num,
                _ => panic!("unexpected message receiving at merge stage"),
            };
            // Sending "merged results" back to the main thread...
            let _ = merged_result_chan.send(PipelineMsg::Merged(squared));
        }
    });
    // Sharing the "merge_chan" with the world...
    chan
}