def METHOD_NAME():
    client = boto3.client("rds", region_name="us-west-2")
    db_identifier = _prepare_db_instance(client)
    client.create_event_subscription(
        SubscriptionName=f"{db_identifier}-events",
        SnsTopicArn=f"arn:aws:sns::{ACCOUNT_ID}:{db_identifier}-events-topic",
    )
    with pytest.raises(ClientError) as ex:
        client.create_event_subscription(
            SubscriptionName=f"{db_identifier}-events",
            SnsTopicArn=f"arn:aws:sns::{ACCOUNT_ID}:{db_identifier}-events-topic",
            Enabled=True,
        )
    err = ex.value.response["Error"]
    assert err["Code"] == "SubscriptionAlreadyExistFault"
    assert err["Message"] == "Subscription db-primary-1-events already exists."