code: def test_arrays_variable_size(self):
      nbits = [10, 5, 3, 12, 6, 7, 4]
      n = 20
      rs = np.random.RandomState(123)
      a = rs.randint(1 << 16, size=(n, len(nbits)), dtype="int32")
      a &= (1 << np.array(nbits)) - 1
      b = faiss.pack_bitstrings(a, nbits)
      c = faiss.unpack_bitstrings(b, nbits)
      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 3 for calling the TestBitstring obj's underlying member method code with example usage: obj.test_arrays_variable_size() without return types