putIfAbsent method
Implementation
dynamic putIfAbsent(dynamic key, Data ifAbsent, {bool notify = true}) {
if (_value is! Map) throw Exception('Cannot insert into not a map');
final res = (_value as Map).putIfAbsent(key, () {
ifAbsent.addParent(this);
return ifAbsent;
});
if (notify) notifyListeners();
return res;
}