anchor.diff:  @Task('Build a Chocolatey package.')
   @Depends(snapshot)
   chocolatey_package() {
  +  if (_isDevSdk) throw "Chocolatey doesn't support dev SDKs.";
  +
     _ensureBuild();
   
     var nuspec = _nuspec();
  
positive.code: /// The [client] is used to download the corresponding Dart SDK.
  Future _buildPackage(http.Client client, String os, String architecture) async {
    // TODO: Compile a single executable that embeds the Dart VM and the snapshot.
    var url = "https://storage.googleapis.com/dart-archive/channels/stable/"
        "release/$_dartVersion/sdk/dartsdk-$os-$architecture-release.zip";
    log("Downloading $url...");
    var response = await client.get(Uri.parse(url));
  
negative.code: 
  /// The version of the current Dart executable.
  final String _dartVersion = Platform.version.split(" ").first;
  
  /// Whether we're using a dev Dart SDK.
  bool get _isDevSdk => _dartVersion.contains("-dev");
  
  /// The root of the Dart SDK.
  final _sdkDir = p.dirname(p.dirname(Platform.resolvedExecutable));
  