diff --git a/dagfactory/dagbuilder.py b/dagfactory/dagbuilder.py
index c5b1f573..311f41e6 100644
--- a/dagfactory/dagbuilder.py
+++ b/dagfactory/dagbuilder.py
@@ -9,7 +9,7 @@
 from copy import deepcopy
 from datetime import datetime, timedelta
 from functools import partial
-from typing import Any, Callable, Dict, List, Union, Optional
+from typing import Any, Callable, Dict, List, Optional, Union
 
 from airflow import DAG, configuration
 from airflow.models import BaseOperator, Variable