|  | // Copyright (c) 2019, 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. | 
|  |  | 
|  | class Class { | 
|  | int? field; | 
|  | int? method() => field; | 
|  | Class operator +(Class other) => new Class(); | 
|  | } | 
|  |  | 
|  | main() { | 
|  | Class? c = new Class() as Class?; | 
|  | c!; | 
|  | c!.field; | 
|  | c!.field = 42; | 
|  | c!.method; | 
|  | c!.method(); | 
|  | c!.field!.toString(); | 
|  | c!.method()!.toString(); | 
|  | c! + c; | 
|  | c! + c!; | 
|  | c + c!; | 
|  | (c + c)!; | 
|  |  | 
|  | bool? o = true as bool?; | 
|  | !o! ? !o! : !!o!!; | 
|  | !(o!) ? (!o)! : (!(!o)!)!; | 
|  | } |