code: def test_is_single_threaded_default_value():
      assert not BaseExecutor.is_single_threaded
  
imports: from __future__ import annotations
  import logging
  import sys
  from datetime import timedelta
  from unittest import mock
  import pendulum
  import pytest
  import time_machine
  from airflow.callbacks.callback_requests import CallbackRequest
  from airflow.cli.cli_config import DefaultHelpParser, GroupCommand
  from airflow.cli.cli_parser import AirflowHelpFormatter
  from airflow.executors.base_executor import BaseExecutor, RunningRetryAttemptType
  from airflow.models.baseoperator import BaseOperator
  from airflow.models.taskinstance import TaskInstance, TaskInstanceKey
  from airflow.utils import timezone
  from airflow.utils.state import State
label_desc: Use image node_id 4 for calling a global function with example usage: test_is_single_threaded_default_value() without return types