code: def joinSite(self, machineAdminUrl,
                   username, password):
          
          params = {
              "machineAdminUrl" : machineAdminUrl,
              "username" : username,
              "password" : password,
              "f" : "json"
          }
          url = self._url + "/joinSite"
          return self._post(url=url, param_dict=params)
docs: The joinSite operation connects a portal machine to an existing
          site. You must provide an account with administrative privileges to
          the site for the operation to be successful.