code: def close(self):
      if self._periodic_flusher:
          self._periodic_flusher.cancel()
          self._periodic_flusher = None
  
file_path: flink/flink-python/pyflink/fn_execution/beam/beam_stream_slow.py
imports: from apache_beam.coders.coder_impl import create_InputStream, create_OutputStream
  from pyflink.fn_execution.stream_slow import InputStream
  from pyflink.fn_execution.utils.operation_utils import PeriodicThread
label_desc: Use image node_id 5 for calling the BeamTimeBasedOutputStream obj's underlying member method code with example usage: obj.close() without return types