[Exposed=*]
interface Subscriber {
  undefined next(any value);
  undefined error(any error);
  undefined complete();
  undefined addTeardown(VoidFunction teardown);
  readonly attribute boolean active;
  readonly attribute AbortSignal signal;
};


callback SubscribeCallback = undefined (Subscriber subscriber);
callback SubscriptionObserverCallback = undefined (any value);

dictionary SubscriptionObserver {
  SubscriptionObserverCallback next;
  SubscriptionObserverCallback error;
  VoidFunction complete;
};

typedef (SubscriptionObserverCallback or Observer) ObserverUnion;

dictionary SubscribeOptions {
  AbortSignal signal;
};

[Exposed=*]
interface Observable {
  constructor(SubscribeCallback callback);
  undefined subscribe(optional ObserverUnion observer = {}, optional SubscribeOptions options = {});
};