format method
Format the Day's displaying.
For more details, view: https://github.com/dayjs/day.dart/blob/master/API.md#format-format
Implementation
String format([String? format]) {
if (format == null) {
return toIso8601String();
}
return format.replaceAllMapped(RegExp(dayDartRegexpFormat),
(Match m) => u.processMatchFromFormat(m, this));
}