code: def snapshot(self, snapshot_file: str):
      self.logger.warning(
          f"Snapshotting to {snapshot_file} with {len(self._docs)} documents"
      )
      self.logger.warning(
          f"Snapshotting with order {[d.text for d in self._docs]}"
      )
      with open(snapshot_file, "wb") as f:
          self._docs.save_binary(f)
  
file_path: jina/tests/integration/stateful/stateful_snapshot_exec/executor.py
imports: from jina import DocumentArray, Executor, requests
  from jina.serve.executors.decorators import write
  import random
  from typing import Dict, List
  import os
  from docarray.documents import TextDoc
label_desc: Use image node_id 5 for calling the MyStateExecutor obj's underlying member method code with example usage: obj.snapshot(snapshot_file) without return types