code: def test_getTotalNumImages(self):
      totalNumOfImages = self.imageDataExtractor.getTotalNumImages()
      print(totalNumOfImages)
      self.assertEqual(len(self.nameToImageData), totalNumOfImages)
  
imports: import sys
  import unittest
  from typing import Dict, List
  from MONAILabelReviewerLib.ImageData import ImageData
  from MONAILabelReviewerLib.ImageDataExtractor import ImageDataExtractor
  from MONAILabelReviewerLib.MONAILabelReviewerEnum import Level, SegStatus
label_desc: Use image node_id 4 for calling the ImageDataExtractorTest obj's underlying member method code with example usage: obj.test_getTotalNumImages() without return types