logout method
logs out user. use this before login if user is already logged in
Implementation
Future<void> logout() async {
EventModel event = EventModel(
name: Constants.logout,
eventTime: DateTime.now().millisecondsSinceEpoch + 1);
_database.insertEvent(event).then((value) async {
if (_session.data!.stime == null ||
_isSessionExpired(_session.data!.stime!)) {
await _createSession();
}
await _flushEvents();
});
}