code: def test_copy_bitpacked_buffer_if_needed():
      M = 20
      n = M * 8
      # Represent an integer as a pyarrow buffer of bytes.
      bytes_ = (n * 8).to_bytes(M, sys.byteorder)
      buf = pa.py_buffer(bytes_)
      for offset in range(0, n - 1):
          for length in range(1, n - offset):
              copied_buf = _copy_bitpacked_buffer_if_needed(
                  buf, offset, length
              )
              if offset > 0:
                  assert copied_buf.address != buf.address
              else:
                  assert copied_buf.address == buf.address
              # Buffer needs to include bits remaining in byte after adjusting for bit
              # offset..
              assert (
                  copied_buf.size
                  == ((length + (offset % 8) - 1) // 8) + 1
              )
  
imports: import logging
  import os
  import sys
  from unittest import mock
  import numpy
  import pyarrow
  import pyarrow.parquet
  import pytest
  from packaging.version import parse
  from pytest_lazyfixture import lazy_fixture
  import ray
  import ray.cloudpickle
  from ray._private.arrow_serialization import _align_bit_offset, _bytes_for_bits, _copy_bitpacked_buffer_if_needed, _copy_buffer_if_needed, _copy_normal_buffer_if_needed, _copy_offsets_buffer_if_needed
  from ray._private.utils import _get_pyarrow_version
  from ray.data.extensions.tensor_extension import ArrowTensorArray, ArrowVariableShapedTensorArray
  from ray.tests.conftest import *
label_desc: Use image node_id 6 for calling a global function with example usage: test_copy_bitpacked_buffer_if_needed() without return types