reserveNamespace static method
Claims prefix for a package: applications are refused it, as they are
refused dv., and the package reaches it through namespace. sealed
keeps every value there encrypted under the application key.
Implementation
static void reserveNamespace(String prefix, {bool sealed = false}) {
if (!_reserved.contains(prefix)) _reserved.add(prefix);
if (sealed && !_sealed.contains(prefix)) _sealed.add(prefix);
}