anchor.diff: -/// 
  +///
   /// Script to create boilerplate for a Polymer element.
   /// Produces new .html entry point for a polymer app and updates the
   /// pubspec.yaml to reflect it.
  -/// 
  +///
   /// Run this script with pub run:
  -/// 
  +///
   ///     pub run polymer:new_entry <html_file>
  -/// 
  +///
   import 'dart:io';
   import 'package:path/path.dart' as path;
   import 'package:yaml/yaml.dart';
   import 'package:source_span/source_span.dart';
   
   void main(List<String> args) {
  -  var entryPoint = args[0];  
  +  var entryPoint = args[0];
     var outputDir = path.dirname(entryPoint);
     var outputDirLocation = new Directory(outputDir);
  -  
  +
     if (!outputDirLocation.existsSync()) {
       outputDirLocation.createSync(recursive: true);
     }
  -  
  +
     outputDir = outputDirLocation.resolveSymbolicLinksSync();
     var pubspecDir = _findDirWithFile(outputDir, 'pubspec.yaml');
  -  
  +
     if (pubspecDir == null) {
       print('Could not find pubspec.yaml when walking up from $outputDir');
       exitCode = 1;
  
positive.code: ''';
  
    new File(path.join(pubspecDir, entryPoint)).writeAsStringSync(html);
    
    var pubspecPath = path.join(pubspecDir, 'pubspec.yaml');
    var pubspecText = new File(pubspecPath).readAsStringSync();
    var transformers = loadYaml(pubspecText)['transformers'];
    var entryPoints = [entryPoint];
  
    var insertionPoint;
    var textToInsert = '';
  
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;
  