code: def _read_stream(self, f: "pa.NativeFile", path: str):
      for block in super()._read_stream(f, path):
          time.sleep(3)
          yield block
  
imports: import os
  import time
  from dataclasses import astuple, dataclass
  import numpy
  import pandas
  import pyarrow
  import pytest
  import ray
  from ray.data import Dataset
  from ray.data._internal.arrow_block import ArrowBlockAccessor
  from ray.data._internal.lazy_block_list import LazyBlockList
  from ray.data.block import BlockMetadata
  from ray.data.datasource import Datasource
  from ray.data.datasource.csv_datasource import CSVDatasource
  from ray.data.datasource.datasource import Reader, ReadTask
  from ray.data.tests.conftest import CoreExecutionMetrics, assert_blocks_expected_in_plasma, assert_core_execution_metrics_equals, get_initial_core_execution_metrics_snapshot
  from ray.tests.conftest import *
label_desc: Use image node_id 1 for calling the SlowCSVDatasource obj's underlying member method code with example usage: obj._read_stream(f, path) without return types