getMany method
Bulk fetch — returns the values for every key in keys that
is currently present. Keys that are absent are NOT included
in the returned map.
Implementation
@override
Future<Map<String, AtNotification>> getMany(List<String> keys) async {
final result = <String, AtNotification>{};
for (final k in keys) {
if (!_getBox().keys.contains(k)) continue;
final value = await getValue(k);
if (value != null) result[k] = value;
}
return result;
}