code: def has_file(self, filename) -> bool:
      if not self.cache_dir:
          raise RuntimeError("Could not create or locate cache dir")
      return os.path.exists(self._make_path(filename))
  
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 3 for calling the FileCacheManager obj's underlying member method code with example usage: obj.has_file(filename) and returns: os