code: function (doc, req) {
           // This function will be used to implement "touch" for `get_avar`.
              var response;
              response = {
                  headers: {
                      'Content-Type': 'application/json'
                  },
                  body: (doc === null) ? '{}' : doc.body
              };
              if (doc instanceof Object) {
                  doc.last_touch = Date.now();
              }
              return [doc, response];
          }
docs: NOTE: Do not out-clever yourself here! You _can_ add the CORS headers in this function, but if you're already doing it inside an external webserver like Nginx or Node.js, it will cause CORS _not_ to work.