code: def dag_setup():
      return DAG(
          f"{TEST_DAG_ID}test_schedule_dag_once",
          default_args={
              "owner": "airflow",
              "start_date": DEFAULT_DATE,
          },
          schedule="@once",
      )
  
imports: from __future__ import annotations
  import pytest
  from opensearchpy import Document, Keyword, Text
  from airflow.models import DAG
  from airflow.providers.opensearch.operators.opensearch import OpenSearchAddDocumentOperator, OpenSearchCreateIndexOperator, OpenSearchQueryOperator
  from airflow.utils.timezone import datetime
label_desc: Use image node_id 1 for calling a global function with example usage: dag_setup() and returns: DAG