code: def get_file_timestamp(self, key):
      key_path: str = self._get_file_path_from_key(key)
      if os.path.exists(key_path):
          return os.path.getmtime(key_path)
      else:
          return None
  
imports: import os
  import shutil
  from typing import Dict
  from studio.storage.storage_setup import get_storage_verbose_level
  from studio.storage.storage_type import StorageType
  from studio.storage.storage_handler import StorageHandler
  from studio.util import logs
  from studio.util import util
label_desc: Use image node_id 10 for calling the LocalStorageHandler obj's underlying member method code with example usage: obj.get_file_timestamp(key) and returns: os, None