code: public function setAccount($iban, $swift = null)
      {
          if ($swift !== null) {
              $iban .= '+' . $swift;
          }
  
          return $this->add('ACC', $iban);
      }
docs: Set account
  
  @param string $iban IBAN
  @param string|null $swift SWIFT
  @return QRPayment
  @throws RuntimeException