code: function(req, res, next) {
      // If we timed out before managing to respond, don't send the response
      if (res.headersSent) {
        return;
      }
  
      // Look for `.json` or `.xml` extension in path
      // And override request accept header
      if (/.json$/.test(req.path)) {
        req.headers.accept = 'application/json';
      } else if (/.xml$/.test(req.path)) {
        req.headers.accept = 'application/xml';
      }
  
      // Use request accept header to determine response content-type
      res.format({
        json: function() {
          res.status(res.code).jsonp(res.data);
        },
        xml: function() {
          var xml;
          try {
            var xmlData = JSON.parse(JSON.stringify(res.data));
            xml = this.xmlBuilder.buildObject(xmlData);
            res.set('Content-Type', 'application/xml; charset=utf-8');
            res.status(res.code).send(xml);
          } catch (e) {
            res.status(500).end();
          }
        }.bind(this)
      });
    }
docs: Final middleware for handling all responses
  Server actually responds and terminates to the request here