code: def test_arrays(self):
      nbit = 5
      M = 10
      n = 20
      rs = np.random.RandomState(123)
      a = rs.randint(1 << nbit, size=(n, M), dtype="int32")
      b = faiss.pack_bitstrings(a, nbit)
      c = faiss.unpack_bitstrings(b, M, nbit)
      np.testing.assert_array_equal(a, c)
  
imports: from __future__ import print_function
  import numpy
  import unittest
  import faiss
  from common_faiss_tests import get_dataset_2
  from faiss.contrib.datasets import SyntheticDataset
  from faiss.contrib.inspect_tools import get_additive_quantizer_codebooks
label_desc: Use image node_id 2 for calling the TestBitstring obj's underlying member method code with example usage: obj.test_arrays() without return types