code: func (w *Wallet) ping() error {
  	w.lock.Lock()
  	defer w.lock.Unlock()
  
  	// We can't ping if not paired
  	if !w.session.paired() {
  		return nil
  	}
  	if _, err := w.session.walletStatus(); err != nil {
  		return err
  	}
  	return nil
  }
docs: // ping checks the card's status and returns an error if unsuccessful.