docstr: this used to cause OOM when training polysemous with large
  nb bits
code: def test_polysemous_OOM(self):
      """this used to cause OOM when training polysemous with large
      nb bits"""
      d = 32
      xt, xb, xq = get_dataset_2(d, 10000, 0, 0)
      index = faiss.IndexPQ(d, M, 13)
      index.do_polysemous_training = True
      index.pq.cp.niter = 0
      index.polysemous_training.max_memory = 128 * 1024 * 1024
      self.assertRaises(RuntimeError, index.train, xt)
  
imports: from __future__ import absolute_import, division, print_function
  import unittest
  import faiss
  import numpy
  from common_faiss_tests import Randu10k, get_dataset_2, Randu10kUnbalanced
label_desc: Use image node_id 12 for calling the IndexAccuracy obj's underlying member method code with example usage: obj.test_polysemous_OOM() without return types