diff --git a/examples/highfreq/highfreq_handler.py b/examples/highfreq/highfreq_handler.py
index 111fe57bf..19bb2550b 100644
--- a/examples/highfreq/highfreq_handler.py
+++ b/examples/highfreq/highfreq_handler.py
@@ -2,7 +2,6 @@ from qlib.data.dataset.handler import DataHandler, DataHandlerLP
 from qlib.contrib.data.handler import check_transform_proc
 
 
-
 class HighFreqHandler(DataHandlerLP):
     def __init__(
         self,