function Subscription(unsubscribe) {
        /**
         * A flag to indicate whether this Subscription has already been unsubscribed.
         * @type {boolean}
         */
        this.closed = false;
        this._parent = null;
        this._parents = null;
        this._subscriptions = null;
        if (unsubscribe) {
            this._unsubscribe = unsubscribe;
        }
    }
/**
     * @param {function(): void} [unsubscribe] A function describing how to
     * perform the disposal of resources when the `unsubscribe` method is called.
     */
@param {function(): void} [unsubscribe] A function describing how to
perform the disposal of resources when the `unsubscribe` method is called.
@param { function () : void } [ unsubscribe ] A function describing how to perform the disposal of resources when the ` unsubscribe ` method is called .
function Subscription(unsubscribe) {
        this.closed = false;
        this._parent = null;
        this._parents = null;
        this._subscriptions = null;
        if (unsubscribe) {
            this._unsubscribe = unsubscribe;
        }
    }
function Subscription ( unsubscribe ) { this . closed = false ; this . _parent = null ; this . _parents = null ; this . _subscriptions = null ; if ( unsubscribe ) { this . _unsubscribe = unsubscribe ; } }
@param {function(): void} [unsubscribe] A function describing how to
 perform the disposal of resources when the `unsubscribe` method is called.
@param { function () : void } [ unsubscribe ] A function describing how to perform the disposal of resources when the ` unsubscribe ` method is called .
/**
         * A flag to indicate whether this Subscription has already been unsubscribed.
         * @type {boolean}
         */