code: def _read_stream(
      self, f: "pyarrow.NativeFile", path: str
  ) -> Iterator[Block]:
      builder = DelegatingBlockBuilder()
      builder.add({"data": f.readall()})
      yield builder.build()
  
file_path: ray/python/ray/data/tests/test_file_based_datasource.py
imports: import os
  from typing import Iterator
  from unittest import mock
  import pyarrow
  import pytest
  import ray
  from ray.data._internal.delegating_block_builder import DelegatingBlockBuilder
  from ray.data.block import Block
  from ray.data.datasource.file_based_datasource import OPEN_FILE_MAX_ATTEMPTS, FileBasedDatasource, _open_file_with_retry
  from ray.data.datasource.path_util import _is_local_windows_path
label_desc: Use image node_id 1 for calling the MockFileBasedDatasource obj's underlying member method code with example usage: obj._read_stream(f, path) without return types