code: def test_dag():
      """Creates a test DAG with a few operators to test on."""
  
      def f(task_id):
          return f"OP:{task_id}"
  
      with DAG(
          dag_id="test_xcom_dag", default_args=DEFAULT_ARGS
      ) as dag:
          operators = [
              PythonOperator(python_callable=f, task_id=f"test_op_{i}")
              for i in range(4)
          ]
          return dag, operators
  
imports: from __future__ import annotations
  from datetime import datetime, timedelta
  import pytest
  from airflow.models.dag import DAG
  from airflow.models.xcom_arg import XComArg
  from airflow.operators.empty import EmptyOperator
  from airflow.operators.python import PythonOperator
  from airflow.utils.edgemodifier import Label
  from airflow.utils.task_group import TaskGroup
  from airflow.www.views import dag_edges
label_desc: Use image node_id 1 for calling a global function with example usage: test_dag() and returns: str, task_id, dag,  operators