auto [tx, rx] = xpp::sync::mpsc::channel<int>(8);

// Consumer fiber — drains the channel, prints sum
auto consumer = xpp::fiber([rx = std::move(rx)]() mutable {
  int sum = 0;
  while (true) {
    auto val = rx.recv().await();      // suspends until data arrives
    if (val.is_none()) break;          // channel closed — all done
    sum += val.unwrap();
  }
  printf("sum: %d\n", sum);            // 210
});

// Two producer fibers send concurrently over the same channel
auto p1 = xpp::fiber([tx]() {
  for (int i =  1; i <= 10; i++) tx.send(i).await();
});
auto p2 = xpp::fiber([tx]() {
  for (int i = 11; i <= 20; i++) tx.send(i).await();
});

// Wait for producers, then signal consumer
xpp::all(std::move(p1), std::move(p2))
    .then([tx = std::move(tx)]() mutable { tx.close(); })
    .await();

consumer.await();