docstr: Download source_dir to target_dir.
docstr_tok: ["Download","source_dir","to","target_dir","."]
code: def download(self, source: str, target: str):
      """Download source_dir to target_dir."""
      raise NotImplementedError
  
file_path: ray/release/ray_release/file_manager/file_manager.py
imports: import abc
  from typing import Optional
  from ray_release.cluster_manager.cluster_manager import ClusterManager
label_desc: Use image node_id 3 for calling the FileManager obj's underlying member method code with example usage: obj.download(source, target) without return types