diff --git a/examples/highfreq/workflow.py b/examples/highfreq/workflow.py
index dac27082f..ff3d3c552 100644
--- a/examples/highfreq/workflow.py
+++ b/examples/highfreq/workflow.py
@@ -26,6 +26,7 @@ from qlib.tests.data import GetData
 
 from highfreq_ops import get_calendar_day, DayLast, FFillNan, BFillNan, Date, Select, IsNull
 
+
 class HighfreqWorkflow(object):
 
     SPEC_CONF = {"custom_ops": [DayLast, FFillNan, BFillNan, Date, Select, IsNull], "expression_cache": None}
@@ -146,29 +147,29 @@ class HighfreqWorkflow(object):
         self._prepare_calender_cache()
         ##=============reinit dataset=============
         dataset.init(
-            handler_kwargs = {
-                "init_type" : DataHandlerLP.IT_LS,
-                "start_time" : "2021-01-19 00:00:00",
-                "end_time" : "2021-01-25 16:00:00",
+            handler_kwargs={
+                "init_type": DataHandlerLP.IT_LS,
+                "start_time": "2021-01-19 00:00:00",
+                "end_time": "2021-01-25 16:00:00",
             },
-            segment_kwargs = {
+            segment_kwargs={
                 "test": (
-                    "2021-01-19 00:00:00", 
+                    "2021-01-19 00:00:00",
                     "2021-01-25 16:00:00",
                 ),
-            }
+            },
         )
         dataset_backtest.init(
-            handler_kwargs = {
-                "start_time" : "2021-01-19 00:00:00",
-                "end_time" : "2021-01-25 16:00:00",
+            handler_kwargs={
+                "start_time": "2021-01-19 00:00:00",
+                "end_time": "2021-01-25 16:00:00",
             },
-            segment_kwargs = {
+            segment_kwargs={
                 "test": (
-                    "2021-01-19 00:00:00", 
+                    "2021-01-19 00:00:00",
                     "2021-01-25 16:00:00",
                 ),
-            }
+            },
         )
 
         ##=============get data=============
diff --git a/qlib/data/dataset/__init__.py b/qlib/data/dataset/__init__.py
index e2606ec0f..8ff8c1210 100644
--- a/qlib/data/dataset/__init__.py
+++ b/qlib/data/dataset/__init__.py
@@ -87,19 +87,19 @@ class DatasetH(Dataset):
         """
         super().__init__(handler, segments)
 
-    def init(self, handler_kwargs:dict = None, segment_kwargs:dict = None):
+    def init(self, handler_kwargs: dict = None, segment_kwargs: dict = None):
         """
         Initialize the DatasetH
-        
+
         Parameters
         ----------
         handler_kwargs : dict
             Config of DataHanlder, which could include the following arguments:
-            
+
             - arguments of DataHandler.conf_data, such as 'instruments', 'start_time' and 'end_time'.
 
             - arguments of DataHandler.init, such as 'enable_cache', etc.
-        
+
         segment_kwargs : dict
             Config of segments which is same as 'segments' in DatasetH.setup_data
 
@@ -112,10 +112,10 @@ class DatasetH(Dataset):
             conf_data_arg = {"instruments", "start_time", "end_time"}
             for k, v in handler_kwargs.items():
                 if k in conf_data_arg:
-                    kwargs_conf_data.update({k:v})
+                    kwargs_conf_data.update({k: v})
                 else:
-                    kwargs_init.update({k:v})
-            
+                    kwargs_init.update({k: v})
+
             self.handler.conf_data(**kwargs_conf_data)
             self.handler.init(**kwargs_init)