code: def get_file(self, filename) -> Optional[str]:
      if self.has_file(filename):
          return self._make_path(filename)
      else:
          return None
  
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 4 for calling the FileCacheManager obj's underlying member method code with example usage: obj.get_file(filename) and returns: self, None