anchor.diff:    return dir;
   }
   
  -// Returns true if there was a monolithic polymer transformer in the pubspec,
  -// in which case the pubspec wasn't modified. Returns false otherwise.
  +// Returns true if the pubspec file was modified. It might not be modified if
  +// there was a monolithic polymer transformer in the pubspec, or if the entry
  +// point for some reason already existed in the pubspec.
   bool _createBoilerPlate(String entryPoint, String pubspecDir) {
  - 
  +
   String html = '''
   <!doctype html>
   <html>
  
positive.code: 
    var relativeEntryPoint = path.relative(
        path.join(outputDir, path.basename(entryPoint)), from: pubspecDir);
    
    try {
      if (_createBoilerPlate(relativeEntryPoint, pubspecDir) == false) {
        print('Added $entryPoint to ${path.join(pubspecDir, "pubspec.yaml")}');
      }
      print('Successfully created:');
  
negative.code:     // transformers, get the entry points, and delete the old entry points.
      var transformersSourceSpan = transformers.span;
      SourceSpan sourceSpan;
  
      for (var e in transformers) {
        if (e != 'polymer' && (e is! YamlMap || e['polymer'] == null)) continue;
        if (e == 'polymer' || !e['polymer'].containsKey('entry_points')) {
          if (path.split(entryPoint)[0] != 'web') {
            print('WARNING: Did not add entry_point $entryPoint to pubspec.yaml'
                ' because of already-existing transformer|polymer section');
          }
          return false;
        } else if (e['polymer'].keys.length > 1) {
          // TODO(dgrove): handle the case where there are additional sections
          // in the polymer transformer.
          throw new UnimplementedError('Cannot handle non-entry_point entries '
              'for polymer transformer');
        } else {
          var existing = e['polymer']['entry_points'];
          entryPoints = existing == null ? [] :
              (existing is String ? [existing] : existing.toList());
  
          if (entryPoints.contains(entryPoint)) return false;
          entryPoints.add(entryPoint);
  
          sourceSpan = e.span;
        }
      }
  
      if (sourceSpan == null) {
        // There were no polymer transformers.
        insertionPoint = transformersSourceSpan.start.offset;
  