diff --git a/mmaction/utils/typing_utils.py b/mmaction/utils/typing_utils.py
index 4942cc1fd5..ec3efae907 100644
--- a/mmaction/utils/typing_utils.py
+++ b/mmaction/utils/typing_utils.py
@@ -18,7 +18,6 @@
 InstanceList = List[InstanceData]
 OptInstanceList = Optional[InstanceList]
 
-
 SampleList = List[ActionDataSample]
 OptSampleList = Optional[SampleList]