docstr: check that the error is in the same ballpark as PQ.
docstr_tok: ["check","that","the","error","is","in","the","same","ballpark","as","PQ","."]
code: def test_codec(self):
      """check that the error is in the same ballpark as PQ."""
      ds = datasets.SyntheticDataset(64, 3000, 3000, 0)
  
      xt = ds.get_train()
      xb = ds.get_database()
  
      nsplits = 2
      Msub = 2
      nbits = 4
  
      plsq = faiss.ProductLocalSearchQuantizer(
          ds.d, nsplits, Msub, nbits
      )
      plsq.train(xt)
      err_plsq = eval_codec(plsq, xb)
  
      pq = faiss.ProductQuantizer(ds.d, nsplits * Msub, nbits)
      pq.train(xt)
      err_pq = eval_codec(pq, xb)
  
      print(err_plsq, err_pq)
      self.assertLess(err_plsq, err_pq)
  
imports: import numpy
  import faiss
  import unittest
  from faiss.contrib import datasets
label_desc: Use image node_id 1 for calling the TestProductLocalSearchQuantizer obj's underlying member method code with example usage: obj.test_codec() without return types