diff --git a/dargs/dargs.py b/dargs/dargs.py
index d65f105..86eb8ee 100644
--- a/dargs/dargs.py
+++ b/dargs/dargs.py
@@ -16,7 +16,6 @@
 We also need to pay special attention to flat the keys of its choices.
 """
 
-
 import fnmatch
 import json
 import re
diff --git a/dargs/sphinx.py b/dargs/sphinx.py
index 986f743..5fe46e2 100644
--- a/dargs/sphinx.py
+++ b/dargs/sphinx.py
@@ -19,6 +19,7 @@
 
 where `_test_argument` returns an :class:`Argument <dargs.Argument>`. A :class:`list` of :class:`Argument <dargs.Argument>` is also accepted.
 """
+
 import sys
 from typing import ClassVar, List