libphonenumber\PhoneNumber::setPreferredDomesticCarrierCode PHP Method

    public function setPreferredDomesticCarrierCode($value)
    {
        $this->preferredDomesticCarrierCode = (string) $value;
        return $this;
    }

 public function testSerializingPhoneNumber2()
 {
     $phoneNumber = new PhoneNumber();
     $phoneNumber->setCountryCode(1);
     $phoneNumber->setNationalNumber(1);
     $phoneNumber->setExtension(1);
     $phoneNumber->setItalianLeadingZero(1);
     $phoneNumber->setNumberOfLeadingZeros(1);
     $phoneNumber->setRawInput(1);
     $phoneNumber->setCountryCodeSource(1);
     $phoneNumber->setPreferredDomesticCarrierCode(1);
     $serializedString = serialize($phoneNumber);
     $phoneObject2 = unserialize($serializedString);
     $this->assertTrue($phoneObject2->equals($phoneNumber));
 }