operator + method
numerically add operand
to this phone number
e.g.
PhoneParser.parseRaw('61383208100') + 1 == PhoneParser.parseRaw('61383208101');
Implementation
PhoneNumber operator +(int operand) {
final nsnLength = nsn.length;
final resultNsn = BigInt.parse(nsn) + BigInt.from(operand);
return PhoneNumber(
isoCode: isoCode,
nsn: resultNsn.toString().padLeft(nsnLength, '0'),
);
}