code: def signal_handler():
      pass
  
imports: import concurrent.futures
  import os
  import signal
  from unittest import mock
  from unittest.mock import Mock
  import pytest
  from lightning.fabric.plugins.environments import SLURMEnvironment
  from lightning.fabric.utilities.imports import _IS_WINDOWS
  from lightning.pytorch import Trainer
  from lightning.pytorch.demos.boring_classes import BoringModel
  from lightning.pytorch.trainer.connectors.signal_connector import _SignalConnector
  from lightning.pytorch.utilities.exceptions import SIGTERMException
  from tests_pytorch.helpers.runif import RunIf
label_desc: Use image node_id 9 for calling a global function with example usage: signal_handler() without return types