code: function Response(cb) {
          this.body       = new Buffer(0);
          this.statusCode = 200;
          this.headers    = {};
          this.ended      = false;
          var endHandlers = [];
          if (typeof cb === 'function') { endHandlers.push(cb); }
          this._eventHandlers = {head: [], data: [], end: endHandlers};
      }
docs: Represents a server response.
  @class Response
  @constructor
  @param {Function} cb Callback to be used when the response is
  finished. See the `end` event on the `on` method documentation.
   
  Response body.
  
  @attribute body
  @type Buffer
   
  Response status code (by default, `200`).
  
  @attribute statusCode
  @type Integer
   
  Response headers. Note that the header names are Node-style
  (ie. lowercase).
  
  @attribute headers
  @type Object
   
  Whether the response is finished.
  
  @attribute ended
  @type Boolean