code: def test_buffer_contents(array_factory, read_dictionary):
      # Test that null values are deterministically initialized to zero
      # after a roundtrip through Parquet.
      # See ARROW-8006 and ARROW-8011.
      orig_table = pa.Table.from_pydict({"col": array_factory()})
      bio = io.BytesIO()
      pq.write_table(orig_table, bio, use_dictionary=True)
      bio.seek(0)
      read_dictionary = ["col"] if read_dictionary else None
      table = pq.read_table(
          bio, use_threads=False, read_dictionary=read_dictionary
      )
  
      for col in table.columns:
          [chunk] = col.chunks
          buf = chunk.buffers()[1]
          assert buf.to_pybytes() == buf.size * b"\0"
  
imports: from collections import OrderedDict
  import io
  import warnings
  from shutil import copytree
  import numpy
  import pytest
  import pyarrow
  from pyarrow import fs
  from pyarrow.filesystem import LocalFileSystem, FileSystem
  from pyarrow.tests import util
  from pyarrow.tests.parquet.common import _check_roundtrip, _roundtrip_table, _test_dataframe
label_desc: Use image node_id 32 for calling a global function with example usage: test_buffer_contents(array_factory, read_dictionary) without return types