| // Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file | |
| // for details. All rights reserved. Use of this source code is governed by a | |
| // BSD-style license that can be found in the LICENSE file. | |
| part of dart._internal; | |
| external T createSentinel<T>(); | |
| external bool isSentinel(dynamic value); |