anchor.diff:  import 'dart:convert' show JSON;
  -import 'dart:io' show Directory, File, Process, exitCode;
  +import 'dart:io' show Directory, File, Platform, Process, exitCode;
   
   import 'package:args/args.dart' show ArgParser;
   import 'package:path/path.dart' show absolute;
  
positive.code:     print("==========================================================");
      print("Running dartdoc for $markdownRef...");
      print("==========================================================");
      _doInPath(dartdocDir, () => _updateDartdocPubspec(markdownRef));
      return _doInPath(path, () {
        if (!sdk) {
          _system('pub', ['get']);
        }
        var out = Directory.systemTemp
            .createTempSync("dartdoc-compare-${markdownRef}__");
  
negative.code:     // make modifiable copy
      dartdocPubspec = JSON.decode(JSON.encode(dartdocPubspec)) as Map;
  
      if (markdownRef == 'local') {
        dartdocPubspec['dependencies']['markdown'] = {
          'path': markdownPath,
        };
      } else {
        dartdocPubspec['dependencies']['markdown'] = {
          'git': {
            'url': 'git://github.com/dart-lang/markdown.git',
            'ref': markdownRef
          }
        };
      }
  
      new File(dartdocPubspecPath).writeAsStringSync(JSON.encode(dartdocPubspec));
      return _system('pub', ['upgrade']);
    }
  }
  
  