Method isSubscribed

packages/context/src/context.ts:436–438

* Check if an observer is subscribed to this context * @param observer - Context observer

(observer: ContextObserver)

   * @param observer - Context observer
   */
  isSubscribed(observer: ContextObserver) {
    return this.subscriptionManager.isSubscribed(observer);
  }

  /**
   * Create a view of the context chain with the given binding filter