code: def test_merge_IndexFastScan_even_M(self):
      self.do_fast_scan_test("PQ10x4fs", 500)
  
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 10 for calling the TestMerge2 obj's underlying member method code with example usage: obj.test_merge_IndexFastScan_even_M() without return types