code: def check_iterator_list(di_list):
      di_size = [di.size for di in di_list]
      assert len(set(di_size)) == 1
  
imports: from __future__ import absolute_import
  import os
  import pytest
  import threading
  import numpy
  from nnabla.logger import logger
  from nnabla.config import nnabla_config
  from nnabla.utils.data_source_loader import load_image
  from nnabla.utils.data_iterator import data_iterator_csv_dataset
  from nnabla.utils.data_iterator import data_iterator_simple
  from nnabla.utils.data_iterator import data_iterator_concat_datasets
  from nnabla.utils.data_source_implements import CsvDataSource
  from .conftest import test_data_csv_png_10, test_data_csv_png_20
label_desc: Use image node_id 6 for calling a global function with example usage: check_iterator_list(di_list) without return types