code: def get_cluster_driver() -> Optional[str]:
      return "direct"
  
file_path: pytorch-lightning/src/lightning/app/core/constants.py
imports: import os
  from pathlib import Path
  from typing import Optional
  import lightning_cloud.env
label_desc: Use image node_id 5 for calling a global function with example usage: get_cluster_driver() and returns: str