code: def clear(self):
          
          del self._statements_and_parameters[:]
          self.keyspace = None
          self.routing_key = None
          if self.custom_payload:
              self.custom_payload.clear()
docs: This is a convenience method to clear a batch statement for reuse.
  
          *Note:* it should not be used concurrently with uncompleted execution futures executing the same
          ``BatchStatement``.