code: def test_extension_indexing(self):
      with tempfile.TemporaryDirectory() as tmp_dir:
          my_features = DEFAULT_FEATURES.copy()
          my_features["explicit_ext"] = Array2D((3, 3), dtype="float32")
          with ArrowWriter(
              features=my_features,
              path=os.path.join(tmp_dir, "beta.arrow"),
          ) as writer:
              for key, record in generate_examples(
                  features=my_features, num_examples=1
              ):
                  example = my_features.encode_example(record)
                  writer.write(example)
              num_examples, num_bytes = writer.finalize()
          dataset = datasets.Dataset.from_file(
              os.path.join(tmp_dir, "beta.arrow")
          )
          dataset.set_format("numpy")
          data = dataset[0]["explicit_ext"]
          self.assertIsInstance(
              data,
              np.ndarray,
              "indexed extension must return numpy.ndarray",
          )
          del dataset
  
imports: import os
  import random
  import tempfile
  import unittest
  import numpy
  import pandas
  import pyarrow
  import pytest
  from absl.testing import parameterized
  import datasets
  from datasets.arrow_writer import ArrowWriter
  from datasets.features import Array2D, Array3D, Array4D, Array5D, Value
  from datasets.features.features import Array3DExtensionType, PandasArrayExtensionDtype, _ArrayXD
  from datasets.formatting.formatting import NumpyArrowExtractor, SimpleArrowExtractor
label_desc: Use image node_id 4 for calling the ExtensionTypeCompatibilityTest obj's underlying member method code with example usage: obj.test_extension_indexing() without return types