code: def do_fast_scan_test(self, factory_key, size1):
      ds = SyntheticDataset(110, 1000, 1000, 100)
      index1 = faiss.index_factory(ds.d, factory_key)
      index1.train(ds.get_train())
      index1.reset()
      tokeep = [i % 3 == 0 for i in range(ds.nb)]
      index1.add(ds.get_database()[tokeep])
      _, Iref = index1.search(ds.get_queries(), 5)
      index1.reset()
      index1.add(ds.get_database())
      index1.remove_ids(np.where(np.logical_not(tokeep))[0])
      _, Inew = index1.search(ds.get_queries(), 5)
      np.testing.assert_array_equal(Inew, Iref)
  
imports: import unittest
  import faiss
  import numpy
  from faiss.contrib.datasets import SyntheticDataset
  from common_faiss_tests import Randu10k
label_desc: Use image node_id 1 for calling the TestRemoveFastScan obj's underlying member method code with example usage: obj.do_fast_scan_test(factory_key, size1) without return types