class_docstr: wraps an OnDisk object for use from C++ 
code: def list_size(self, list_no):
      return self.oil.list_size(list_no)
  
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 2 for calling the PyOndiskInvertedLists obj's underlying member method code with example usage: obj.list_size(list_no) and returns: self