anchor.diff:  }
   
   /**
  - * Wrapper around the browser XHR. Use Http service to fetch data
  - * from the server.
  + * The [Http] service facilitates communication with the remote HTTP servers.  It
  + * uses dart:html's [HttpRequest] and provides a number of features on top
  + * of the core Dart library.
  + *
  + * For unit testing, applications should use the [MockHttpBackend] service.
  + *
  + * # General usage
  + * The [call] method takes a number of named parameters and returns a
  + * [Future<HttpResponse>].
  + *
  + *      http(method: 'GET', url: '/someUrl')
  + *        .then((HttpResponse response) { .. },
  + *               onError: (HttpRequest request) { .. });
  + *
  + * A response status code between 200 and 299 is considered a success status and
  + * will result in the 'then' being called. Note that if the response is a redirect,
  + * Dart's [HttpRequest] will transparently follow it, meaning that the error callback will not be
  + * called for such responses.
  + *
  + * # Shortcut methods
  + *
  + * The Http service also defines a number of shortcuts:
  + *
  + *      http.get('/someUrl') is the same as http(method: 'GET', url: '/someUrl')
  + *
  + * See the method definitions below.
  + *
  + * # Setting HTTP Headers
  + *
  + * The [Http] service will add certain HTTP headers to requests.  These defaults
  + * can be configured using the [HttpDefaultHeaders] object.  The defaults are:
  + *
  + * - For all requests: `Accept: application/json, text/plain, * / *`
  + * - For POST, PUT, PATCH requests: `Content-Type: application/json`
  + *
  + * # Transforming Requests and Responses
  + *
  + *  NOTE: < use interceptors >.
  + *
  + * # Caching
  + *
  + * To enable caching, pass a [Cache] object into the [call] method.  The [Http]
  + * service will store responses in the cache and return the response for
  + * any matching requests.
  + *
  + * Note that data is returned through a [Future], regardless of whether it
  + * came from the [Cache] or the server.
  + *
  + * If there are multiple GET requests for the same not-yet-in-cache URL
  + * while a cache is in use, only one request to the server will be made.
  + *
  + * # Interceptors
  + *
  + * NOTE: < not yet implemented >
  + *
  + * # Security Considerations
  + *
  + * NOTE: < not yet documented >
    */
   class Http {
     Map<String, async.Future<HttpResponse>> _pendingRequests = <String, async.Future<HttpResponse>>{};
  
positive.code:     });
    }
  
    async.Future<HttpResponse> get(String url, {
      String data,
      Map<String, dynamic> params,
  
negative.code:              transformRequest: transformRequest, transformResponse: transformResponse,
               cache: cache, timeout: timeout);
  
    /**
     * Shortcut method for HEAD requests.  See [call] for a complete description
     * of parameters.
     */
    async.Future<HttpResponse> head(String url, {
      String data,
      Map<String, dynamic> params,
  