code: def test_initialize(self, fh_enable_mock):
      ErrorHandler().initialize()
      fh_enable_mock.assert_called_once()
  
imports: import filecmp
  import json
  import os
  import shutil
  import tempfile
  import unittest
  from unittest.mock import patch
  from torch.distributed.elastic.multiprocessing.errors.error_handler import ErrorHandler
  from torch.distributed.elastic.multiprocessing.errors.handlers import get_error_handler
label_desc: Use image node_id 3 for calling the ErrorHandlerTest obj's underlying member method code with example usage: obj.test_initialize(fh_enable_mock) without return types