anchor.diff:    final String dartdocBin;
     final String dartdocPubspecPath;
     final bool sdk;
  +  final String markdownPath = new File(Platform.script.path).parent.parent.path;
   
     DartdocCompare(this.dartdocDir, this.markdownBefore, this.markdownAfter,
         this.dartdocBin, this.dartdocPubspecPath, this.sdk);
   
     bool compare(String package) {
  -    // Generate docs with Markdown "A".
  +    // Generate docs with Markdown "Before".
       var outBefore = _runDartdoc(markdownBefore, package);
   
  -    // Generate docs with Markdown "B".
  +    // Generate docs with Markdown "After".
       var outAfter = _runDartdoc(markdownAfter, package);
   
       // Compare outputs
  
positive.code:     // make modifiable copy
      dartdocPubspec = JSON.decode(JSON.encode(dartdocPubspec)) as Map;
  
      dartdocPubspec['dependencies']['markdown'] = {
        'git': {
          'url': 'git://github.com/dart-lang/markdown.git',
          'ref': markdownRef
        }
      };
  
      new File(dartdocPubspecPath).writeAsStringSync(JSON.encode(dartdocPubspec));
      return _system('pub', ['get']);
    }
  }
  
  
negative.code: 
        if (sdk) {
          args.add('--sdk-docs');
        }
  
        print('Command: $cmd ${args.join(' ')}');
        var startTime = new DateTime.now();
        _system(cmd, args);
        var endTime = new DateTime.now();
        var duration = endTime.difference(startTime).inSeconds;
        print('dartdoc generation for $markdownRef took $duration seconds.');
        print('');
  
        return out.path;
      });
  