code: def _generate_filename(self, file_id: str) -> str:
      filename = ""
      if self._dataset_uuid is not None:
          filename += f"{self._dataset_uuid}_"
      filename += file_id
      if self._file_format is not None:
          filename += f".{self._file_format}"
      return filename
  
file_path: ray/python/ray/data/datasource/filename_provider.py
imports: from typing import Any, Dict, Optional
  from ray.data.block import Block
  from ray.util.annotations import PublicAPI
label_desc: Use image node_id 4 for calling the _DefaultFilenameProvider obj's underlying member method code with example usage: obj._generate_filename(file_id) and returns: filename