dayPeriod property
Persian name of the part of the day, as CLDR divides it for fa:
نیمهشب from 0:00, بامداد from 1:00, صبح from 4:00, ظهر from 12:00,
عصر from 13:00, and شب from 19:00.
The same as the B token of format. Throws StateError when
hasTime is false.
Implementation
String get dayPeriod => switch (_time.hour) {
0 => 'نیمهشب',
< 4 => 'بامداد',
< 12 => 'صبح',
12 => 'ظهر',
< 19 => 'عصر',
_ => 'شب',
};