code: def _get_custom_log_dir(custom_log_dir: str, session_id: str):
      if custom_log_dir == "auto":
          return tempfile.mkdtemp(prefix=f"marslog-{session_id}")
      elif custom_log_dir is None:
          return
      else:
          return os.path.join(custom_log_dir, session_id)
  
file_path: mars/mars/services/session/worker/custom_log.py
imports: import os
  import shutil
  import tempfile
  from typing import Any, Dict, List
  from ....None import oscar
  from ....lib.aio import AioFileObject
label_desc: Use image node_id 2 for calling the CustomLogActor obj's underlying member method code with example usage: obj._get_custom_log_dir(custom_log_dir, session_id) and returns: tempfile, os