code: def test_pre_transform(self):
      index = faiss.index_factory(123, "PCAR100,L2Norm,PCAW50,LSHr")
      self.assertTrue(index.chain.size() == 3)
  
imports: import numpy
  import unittest
  import gc
  import faiss
  from faiss.contrib import factory_tools
  from faiss.contrib import datasets
label_desc: Use image node_id 3 for calling the TestFactoryV2 obj's underlying member method code with example usage: obj.test_pre_transform() without return types