如何在Swift Combine中创建自定义链？

struct MyOperator: Publisher {
    typealias Output = Int
    typealias Failure = Never
    
    private let upstream: AnyPublisher<Int, Never>
    
    init(upstream: AnyPublisher<Int, Never>) {
        self.upstream = upstream
    }
    
    func receive<S>(subscriber: S) where S : Subscriber, MyOperator.Failure == S.Failure, MyOperator.Output == S.Input {
        // 实现自定义操作符的逻辑
        let subscription = MyOperatorSubscription(subscriber: subscriber, upstream: upstream)
        subscriber.receive(subscription: subscription)
    }
}

extension Publisher {
    func myOperator() -> MyOperator {
        return MyOperator(upstream: self.eraseToAnyPublisher())
    }
}

class MyOperatorSubscriber: Subscriber {
    typealias Input = Int
    typealias Failure = Never
    
    private var subscription: Subscription?
    
    func receive(subscription: Subscription) {
        self.subscription = subscription
        subscription.request(.unlimited)
    }
    
    func receive(_ input: Int) -> Subscribers.Demand {
        // 处理自定义链中的事件
        print("Received value: \(input)")
        return .unlimited
    }
    
    func receive(completion: Subscribers.Completion<Never>) {
        // 处理自定义链中的完成事件
        print("Completed")
    }
}

let publisher = Just(10)
let subscriber = MyOperatorSubscriber()

publisher
    .myOperator()
    .subscribe(subscriber)