anchor.diff:  
   const CHANNELS = const ['dev', 'stable'];
   
  -const SDK_FILES = const [
  -  'sdk/dartsdk-macos-x64-release.zip',
  -  'sdk/dartsdk-macos-ia32-release.zip'
  -];
  -
  -const DARTIUM_FILES = const [
  -  'dartium/dartium-macos-ia32-release.zip',
  -  'dartium/content_shell-macos-ia32-release.zip'
  -];
  -
  -final FILES = []..addAll(SDK_FILES)..addAll(DARTIUM_FILES);
  +const FILES = const [x64File, ia32File, dartiumFile, contentShellFile];
  +
  +const urlBase = 'https://storage.googleapis.com/dart-archive/channels';
  +const x64File = 'sdk/dartsdk-macos-x64-release.zip';
  +const ia32File = 'sdk/dartsdk-macos-ia32-release.zip';
  +const dartiumFile = 'dartium/dartium-macos-ia32-release.zip';
  +const contentShellFile = 'dartium/content_shell-macos-ia32-release.zip';
   
   Future<String> getHash256(
       String channel, String revision, String download) async {
  
positive.code:     revisions[channel] =
          regExp.firstMatch(lines.firstWhere(regExp.hasMatch)).group(1);
    }
  }
  
  Future setHashes(Map revisions, Map hashes) {
    List waitOn = [];
    for (var channel in CHANNELS) {
      hashes[channel] = {};
      for (var file in FILES) {
        waitOn.add(getHash256(channel, revisions[channel], file).then((hash) {
          hashes[channel][file] = hash;
        }));
      }
    }
    return Future.wait(waitOn);
  }
  
  Future writeHomebrewInfo(String channel, String revision) async {
    var revisions = {};
    var hashes = {};
  
    await setCurrentRevisions(revisions);
  
    if (revisions[channel] == revision) {
      print("Channel $channel is already at revision $revision in homebrew.");
      exit(0);
    }
    revisions[channel] = revision;
    await setHashes(revisions, hashes);
    var devVersion = await getVersion('dev', revisions['dev']);
  
    var stableVersion = await getVersion('stable', revisions['stable']);
  
    await (new File('$repository/dartium.rb').openWrite()
      ..write(DartiumFile(revisions, hashes, devVersion, stableVersion))).close();
    await (new File('$repository/dart.rb').openWrite()
      ..write(DartFile(revisions, hashes, devVersion, stableVersion))).close();
  }
  
  String DartiumFile(
      Map revisions, Map hashes, String devVersion, String stableVersion) {
    final urlBase = 'https://storage.googleapis.com/dart-archive/channels';
    final dartiumFile = 'dartium/dartium-macos-ia32-release.zip';
    final contentShellFile = 'dartium/content_shell-macos-ia32-release.zip';
  
    return '''
  require 'formula'
  
  class Dartium < Formula
  
negative.code:   end
  end
  ''';
  
  Future runGit(List<String> args) async {
    print("git ${args.join(' ')}");
  