code: private void startActivity(int requestCode, Context currentContext, Intent intent, Postcard postcard, NavigationCallback callback) {
          if (requestCode >= 0) {  // Need start for result
              if (currentContext instanceof Activity) {
                  ActivityCompat.startActivityForResult((Activity) currentContext, intent, requestCode, postcard.getOptionsBundle());
              } else {
                  logger.warning(Consts.TAG, "Must use [navigation(activity, ...)] to support [startActivityForResult]");
              }
          } else {
              ActivityCompat.startActivity(currentContext, intent, postcard.getOptionsBundle());
          }
  
          if ((-1 != postcard.getEnterAnim() && -1 != postcard.getExitAnim()) && currentContext instanceof Activity) {    // Old version.
              ((Activity) currentContext).overridePendingTransition(postcard.getEnterAnim(), postcard.getExitAnim());
          }
  
          if (null != callback) { // Navigation over.
              callback.onArrival(postcard);
          }
      }
docs: Start activity
  @see ActivityCompat