anchor.diff:          _tryToDeleteTemp,
         );
       }
  -    return _systemTemp;
  -  }
  -}
  +    return _systemTemp!;
  +  }
  +}
  
positive.code: /// Various convenience file system methods.
  class FileSystemUtils {
    FileSystemUtils({
      @required FileSystem fileSystem,
      @required Platform platform,
    }) : _fileSystem = fileSystem,
         _platform = platform;
  
  
negative.code: // Copyright 2014 The Flutter Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  import 'package:file/file.dart';
  import 'package:file/local.dart' as local_fs;
  