code: def test_read_callback(self):
      self.do_read_callback(0)
  
imports: import numpy
  import unittest
  import faiss
  import tempfile
  import os
  import io
  import sys
  import pickle
  from multiprocessing.pool import ThreadPool
label_desc: Use image node_id 6 for calling the TestCallbacks obj's underlying member method code with example usage: obj.test_read_callback() without return types