// 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.

/// @assertion We say that a type T0 is a subtype of a type T1 (written T0 <: T1)
/// when:
/// Left Nullable: if T0 is S0? then:
/// - T0 <: T1 iff S0 <: T1 and Null <: T1
/// @description Check that if type T0 is S0? and S0 <: T1 and Null <: T1 then
/// T0 is subtype of T1.
/// @author sgrekhov@unipro.ru

class T1 {
  const T1();
}
class S0 extends T1 {
  const S0();
}

S0? t0Instance = new S0();
T1? t1Instance = new T1();

const t1Default = const T1();

//# @T0 = S0?
//# @T1 = T1?