fan_out_1.rs

// Handle the msg from the select.
let result = match msg {
    // We got work from the producer...
    MainMsg::FromProducer(ProducerMsg::Incoming(workflow)) => {
        // Send info to the consumer, telling it to expect this piece of work
        // This is really just for testing in this case...
        let _ = consumer_sender.send(ConsumerMsg::ExpectWorkflow(workflow.id));
        if let Some(executor) = executor_queue.pop_front() {
            // Send work to the worker at the front of the qeue.
            let _ = executor.send(ExecutorMsg::Execute(workflow));
            executor_queue.push_back(executor);
        }
        // Start waiting for the next message.
        // Note we're not assigning anything to "result" here...
        continue;
    },
    // We got a result from the consumer,
    // Assign it to "result" for further processing below...
    MainMsg::FromConsumer(msg) => msg
};