code: function(httpServer) {
        this.stop();
  
        var port = isNaN(options.port) ? 3000 : +options.port;
        _httpServer = httpServer || http.createServer(function(req, res) {
          res.setHeader('Access-Control-Allow-Origin', '*');
          res.setHeader('Access-Control-Request-Method', '*');
          res.setHeader('Access-Control-Allow-Methods', 'OPTIONS, GET');
          res.setHeader('Access-Control-Allow-Headers', '*');
          if ( req.method === 'OPTIONS' ) {
            res.writeHead(200);
            res.end();
            return;
          }
        });
        _httpServer.on('request', _handle);
        _httpServer.listen(port, function() {
          debug.log('Listening on '+port);
        });
  
        return _server;
      }
docs: Start listening
  
  @param  {http.Server} [httpServer] An optional server to use
  @return {http.Server}              An instance of http.Server used for listening to requests