src/OrangePaymentSlipData.php
protected function appendCheckDigit($referenceNumber, $notForPayment = false)
    {
        if ($notForPayment === true) {
            return $referenceNumber . 'X';
        }
        return $referenceNumber . $this->modulo10($referenceNumber);
    }
protected function appendCheckDigit($referenceNumber, $notForPayment = false)
    {
        if ($notForPayment === true) {
            return $referenceNumber . 'X';
        }
        return $referenceNumber . $this->modulo10($referenceNumber);
    }
protected function appendCheckDigit ( $ referenceNumber , $ notForPayment = false ) { if ( $ notForPayment === true ) { return $ referenceNumber . 'X' ; } return $ referenceNumber . $ this -> modulo10 ( $ referenceNumber ) ; }
Append the check digit to the reference number

Simply appends an 'X' if the slip is not meant for payment.

@param string $referenceNumber The reference number to calculate the prefix with.
@param bool $notForPayment Whether the payment slip is not ment for payment.
@return string The reference number with the appended check digit.
Append the check digit to the reference number