code: def set_ttl(self, ttl):
          
          if self._client._session_timeout != ttl:
              self._client._session_timeout = ttl
              self._client.restart()
              return True
docs: It is not possible to change ttl (session_timeout) in zookeeper without
          destroying old session and creating the new one. This method returns `!True`
          if session_timeout has been changed (`restart()` has been called).