guessZoneId function
Obtains an identifier string for the current time zone.
There is no way to obtain an actual time zone ID in Dart. The obtained value if platform dependant and usually human readable.
Implementation
ZoneId guessZoneId() {
var dateTime = DateTime.now();
var zoneName = dateTime.timeZoneName;
var zoneId = ZoneId();
zoneId.value = zoneName;
return zoneId;
}