code: protected static void registerForPushNotification(Context context) {
          if (checkPlayService(context)) {
              WonderPushFirebaseMessagingService.fetchInstanceId();
          } else {
              Log.w(TAG, "Google Play Services not present. Check your setup. If on an emulator, use a Google APIs system image.");
          }
      }
docs: Helper method that will register a device for Google Cloud Messaging
  notification and register the device token to WonderPush. This method is
  called within {@link WonderPush#initialize(Context, String, String)}.
  
  @param context
  The current {@link Activity} (preferred) or {@link Application} context.