anchor.diff:  // Copyright (c) 2016, 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.
  -import 'package:path/path.dart' as pathos;
  +import 'package:path/path.dart' as p;
   
   /// Identifies an asset within a package.
   class AssetId implements Comparable<AssetId> {
  
positive.code: }
  
  String _normalizePath(String path) {
    if (pathos.isAbsolute(path)) {
      throw new ArgumentError('Asset paths must be relative, but got "$path".');
    }
  
  
negative.code:   path = path.replaceAll(r"\", "/");
  
    // Collapse "." and "..".
    return p.posix.normalize(path);
  }
  