code: def test_micro_batching_handler_threads(handler):
      assert len(handler.handle.thread_groups["preprocess"]) == 1
      assert len(handler.handle.thread_groups["inference"]) == 2
      assert len(handler.handle.thread_groups["postprocess"]) == 3
  
imports: import json
  import math
  import random
  import sys
  from pathlib import Path
  import pytest
  from torchvision.models.resnet import ResNet18_Weights
  from ts.handler_utils.micro_batching import MicroBatching
  from ts.torch_handler.image_classifier import ImageClassifier
  from ts.torch_handler.unit_tests.test_utils.mock_context import MockContext
  from ts.torch_handler.unit_tests.test_utils.model_dir import copy_files, download_model
label_desc: Use image node_id 12 for calling a global function with example usage: test_micro_batching_handler_threads(handler) without return types