code: function (callbackFn) {
                  var self = this;
                  request.post(this.options.hostAndPort + '/phantom/functions/args', {
                          form:{
                          }
                      },
                      function (error, response, body) {
                          if (response.statusCode === 200) {
                              callbackFn && callbackFn.call(self, body);
                          }
                          else {
                              console.error(body);
                              throw new Error(body);
                          }
                      });
              }
docs: system calls