code: def setup_class(cls):
      cls.dag = DAG(
          "test_dag",
          default_args={"owner": "airflow", "start_date": DEFAULT_DATE},
      )
      cls.hook = RdsHook(aws_conn_id=AWS_CONN, region_name="us-east-1")
  
imports: from __future__ import annotations
  from moto import mock_rds
  from airflow.models import DAG
  from airflow.providers.amazon.aws.hooks.rds import RdsHook
  from airflow.providers.amazon.aws.sensors.rds import RdsBaseSensor, RdsDbSensor, RdsExportTaskExistenceSensor, RdsSnapshotExistenceSensor
  from airflow.providers.amazon.aws.utils.rds import RdsDbType
  from airflow.utils import timezone
label_desc: Use image node_id 1 for calling the TestRdsExportTaskExistenceSensor obj's underlying member method code with example usage: obj.setup_class(cls) without return types