code: def test_factory_3(self):
      index = faiss.index_factory(12, "IVF10,PQ4")
      faiss.ParameterSpace().set_index_parameter(index, "nprobe", 3)
      assert index.nprobe == 3
  
      index = faiss.index_factory(12, "PCAR8,IVF10,PQ4")
      faiss.ParameterSpace().set_index_parameter(index, "nprobe", 3)
      assert faiss.downcast_index(index.index).nprobe == 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 TestFactory obj's underlying member method code with example usage: obj.test_factory_3() without return types