code: def supervisor(self):
          
          supervisor = self._cached_client('supervisor')
          if not self._api_supervisor_session:
              self._api_supervisor_session = self.__create_supervisor_session(
                  supervisor,
              )
          return supervisor
docs: Return an authenticated connection for use, open new if required.
  
          Returns:
              SupervisorWebService: New or existing session with the Five9
              Statistics API.