code: def put_group(self, filename: str, group: Dict[str, str]) -> str:
      if not self.cache_dir:
          raise RuntimeError("Could not create or locate cache dir")
      grp_contents = json.dumps({"child_paths": group})
      grp_filename = f"__grp__{filename}"
      return self.put(grp_contents, grp_filename, binary=False)
  
imports: import json
  import os
  import random
  from abc import ABC, abstractmethod
  from pathlib import Path
  from typing import Dict, Optional
  import hashlib
label_desc: Use image node_id 6 for calling the FileCacheManager obj's underlying member method code with example usage: obj.put_group(filename, group) and returns: self