Showing `Sequence.bufferedSubscribe(size)`’s non-guaranteeing of order.

buffered_subscribe_unordered.swift

import CombineExt

let delayedIntPublishers = (0...12).map { index in
	AnyPublisher<Int, Never>.create { subscriber in
		print("Subscribed to \(index)")

		DispatchQueue.main.asyncAfter(deadline: .now() + Double.random(in: 1...3)) {
			subscriber.send(index)
			subscriber.send(completion: .finished)
		}

		return AnyCancellable { print("Unsubscribed to \(index)") }
	}
}

let cancellable = delayedIntPublishers
	.publisher
	.flatMap { $0 }
	.collect(5)
	.sink(receiveValue: { batch in print(batch) })

// Sample output:
// ```
// Subscribed to 0
// Subscribed to 1
// Subscribed to 2
// Subscribed to 3
// Subscribed to 4
// Unsubscribed to 0
// Subscribed to 5
// Unsubscribed to 4
// Subscribed to 6
// Unsubscribed to 1
// Subscribed to 7
// Unsubscribed to 3
// Subscribed to 8
// [0, 4, 1, 3, 2]
// Unsubscribed to 2
// Subscribed to 9
// Unsubscribed to 8
// Subscribed to 10
// Unsubscribed to 5
// Subscribed to 11
// Unsubscribed to 6
// Subscribed to 12
// Unsubscribed to 7
// [8, 5, 6, 7, 11]
// Unsubscribed to 11
// Unsubscribed to 10
// Unsubscribed to 9
// Unsubscribed to 12
// [10, 9, 12]
// ```