_notifyScopeListeners() {
    // We need this check for this._notifyingListeners to be able to work on scope during updates
    // If this check is not here we'll produce endless recursion when something is done with the scope
    // during the callback.
    if (!this._notifyingListeners) {
      this._notifyingListeners = true;
      this._scopeListeners.forEach(callback => {
        callback(this);
      });
      this._notifyingListeners = false;
    }
  }
This will be called on every set call.