diff --git a/qlib/contrib/evaluate_portfolio.py b/qlib/contrib/evaluate_portfolio.py
index 04ddd8db0..b3a770e7c 100644
--- a/qlib/contrib/evaluate_portfolio.py
+++ b/qlib/contrib/evaluate_portfolio.py
@@ -61,7 +61,7 @@ def get_position_value(evaluate_date, position):
     # load close price for position
     # position should also consider cash
     instruments = list(position.keys())
-    instruments = list(set(instruments) - set(["cash"]))  # filter 'cash'
+    instruments = list(set(instruments) - {"cash"})  # filter 'cash'
     fields = ["$close"]
     close_data_df = D.features(
         instruments,
@@ -80,7 +80,7 @@ def get_position_list_value(positions):
     instruments = set()
     for day, position in positions.items():
         instruments.update(position.keys())
-    instruments = list(set(instruments) - set(["cash"]))  # filter 'cash'
+    instruments = list(set(instruments) - {"cash"})  # filter 'cash'
     instruments.sort()
     day_list = list(positions.keys())
     day_list.sort()
diff --git a/qlib/utils/__init__.py b/qlib/utils/__init__.py
index 6640dae2c..3585c5281 100644
--- a/qlib/utils/__init__.py
+++ b/qlib/utils/__init__.py
@@ -212,7 +212,7 @@ def get_cls_kwargs(config: Union[dict, str], module) -> (type, dict):
 
 
 def init_instance_by_config(
-    config: Union[str, dict, object], module=None, accept_types: Union[type, Tuple[type]] = tuple([]), **kwargs
+    config: Union[str, dict, object], module=None, accept_types: Union[type, Tuple[type]] = (), **kwargs
 ) -> object:
     """
     get initialized instance with config