String _adyenKey = "<YOUR_ADYEN_KEY>";
CreditCardMdl _creditCard = CreditCardMdl(
    expiryMonth: "<MM>",
    expiryYear: "<YYYY>",
    holderName: "<HOLDER_NAME>",
    number: "CARD_NUMBER",
    cvc: "<CARD_VERIFICATION_CODE>");

void _handleResult(AdyenEncryptedCardMdl? value) {
  // TODO  
}

AdyenHelperManager()
  .encryptCard(card: _creditCard, adyenKey: _adyenKey)
  .then((value) => _handleResult(value))
  .onError((error, stackTrace) => print(error));