anchor.diff:  // 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.
   
  +// ignore_for_file: prefer_initializing_formals
  +// ignore_for_file: unnecessary_new
  +// ignore_for_file: unnecessary_this
  +// ignore_for_file: unused_field
  +// ignore_for_file: unused_local_variable
  +// ignore_for_file: use_setters_to_change_properties
  +
  +import 'dart:async';
   import 'dart:io';
  -import 'dart:async';
   
   class MockIOSink implements Sink {
     @override
  
positive.code: }
  
  class D {
    IOSink init(filename) {
      IOSink _sinkF = new File(filename).openWrite(); // OK
      return _sinkF;
    }
  
negative.code:       ..add(null)
        ..close();
    }
  }
  