code: def _check_device_number(self, devices):
          '''Check if number of devices is between 2 and 4
  
          :param kwargs: dict -- keyword args in dict
          '''
  
          if len(devices) < 2 or len(devices) > 4:
              msg = 'The number of devices to cluster is not supported.'
              raise ClusterNotSupported(msgf _check_device_number(self, devices):
          '''Check if number of devices is between 2 and 4
  
          :param kwargs: dict -- keyword args in dict
          '''
  
          if len(devices) < 2 or len(devices) > 4:
              msg = 'The number of devices to cluster is not supported.'
              raise ClusterNotSupported(msg)
docs: Check if number of devices is between 2 and 4
  
          :param kwargs: dict -- keyword args in dict