code: def _generate_path(self):
      file_name = str(uuid.uuid4())
      selected_index = mod_hash(file_name, len(self._root_dirs))
      selected_dir = self._root_dirs[selected_index]
      return os.path.join(selected_dir, file_name)
  
file_path: mars/mars/storage/filesystem.py
imports: import os
  import uuid
  from typing import Dict, List, Optional, Tuple
  from ..lib.aio import AioFilesystem
  from ..lib.filesystem import FileSystem, get_fs
  from ..serialization import AioSerializer, AioDeserializer
  from ..utils import mod_hash, implements
  from .base import StorageBackend, ObjectInfo, StorageLevel, register_storage_backend
  from .core import StorageFileObject
label_desc: Use image node_id 4 for calling the FileSystemStorage obj's underlying member method code with example usage: obj._generate_path() and returns: os