serialize method

Implementation

String serialize() {
  var timestamp = date.toUtc().millisecondsSinceEpoch / 1000;
  var offset = timezoneOffset >= 0
      ? '+${timezoneOffset.toString().padLeft(4, "0")}'
      : '-${timezoneOffset.abs().toString().padLeft(4, "0")}';

  return '$name <$email> ${timestamp.toInt()} $offset';
}