code: def request_sensor_sampling_clear(self, req):
          
          f = Future()
          @gen.coroutine
          def _clear_strategies():
              self.clear_strategies(req.client_connection)
              raise gen.Return(('ok',))
  
          self.ioloop.add_callback(lambda: chain_future(_clear_strategies(), f))
          return f
docs: Set all sampling strategies for this client to none.
  
          Returns
          -------
          success : {'ok', 'fail'}
              Whether sending the list of devices succeeded.
  
          Examples
          --------
          ?sensor-sampling-clear
          !sensor-sampling-clear ok