From ee42e7ec0c24499d88efbfaff584de38e88507e0 Mon Sep 17 00:00:00 2001
From: Shinichi Hemmi <50256998+Alnusjaponica@users.noreply.github.com>
Date: Thu, 28 Sep 2023 15:22:28 +0900
Subject: [PATCH] Use `Optional` instead of `Union[*, None]`

Co-authored-by: Gen <54583542+gen740@users.noreply.github.com>
---
 optuna/integration/sklearn.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/optuna/integration/sklearn.py b/optuna/integration/sklearn.py
index 95ce56d672..f5a4b7a329 100644
--- a/optuna/integration/sklearn.py
+++ b/optuna/integration/sklearn.py
@@ -52,7 +52,7 @@
 OneDimArrayLikeType = Union[List[float], np.ndarray, "pd.Series"]
 TwoDimArrayLikeType = Union[List[List[float]], np.ndarray, "pd.DataFrame", "spmatrix"]
 IterableType = Union[List, "pd.DataFrame", np.ndarray, "pd.Series", "spmatrix", None]
-IndexableType = Union[Iterable, None]
+IndexableType = Optional[Iterable]
 
 _logger = logging.get_logger(__name__)