@Override
  public void onActivityStopped(Activity activity) {
    // Remove from the current list of running activities
    status.remove(activity.toString());

    // If there are no running activities, the app is backgrounded
    // In this scenario, log the event to Mixpanel
    if (status.isEmpty()) {
      // Send the session tracking information to Mixpanel
      mixpanelCallbacks.track("$app_open");

      // Mark the current session as inactive so we properly start a new one
      mixpanelCallbacks.unregisterSuperProperty("Session");

      // Force all queued Mixpanel data to be sent to Mixpanel
      mixpanelCallbacks.flush();
    }

    Log.d("Current Activities", "onStop() " + status.toString());
  }