code: def _read_stream(
      self, f: pa.NativeFile, path: str
  ) -> Iterator[Block]:
      assert self._block_type in {pd.DataFrame, pa.Table}
  
      if self._block_type is pa.Table:
          from pyarrow import csv
  
          yield csv.read_csv(f)
  
      if self._block_type is pd.DataFrame:
          yield pd.read_csv(f)
  
imports: import json
  import os
  import posixpath
  from typing import Any, Callable, Dict, Iterator, List, Optional, Union
  import pandas
  import pyarrow
  import pyarrow
  import pytest
  from pyarrow.fs import FileType
  from pytest_lazyfixture import lazy_fixture
  import ray
  from ray.data.block import Block
  from ray.data.dataset import Dataset
  from ray.data.datasource import FileBasedDatasource, PathPartitionParser
  from ray.data.datasource.file_based_datasource import FileExtensionFilter, _resolve_paths_and_filesystem
  from ray.data.datasource.partitioning import Partitioning, PartitionStyle, PathPartitionFilter
  from ray.data.tests.conftest import *
  from ray.tests.conftest import *
label_desc: Use image node_id 2 for calling the CSVDatasource obj's underlying member method code with example usage: obj._read_stream(f, path) without return types