diff --git a/optuna_dashboard/preferential/samplers/__init__.py b/optuna_dashboard/preferential/samplers/__init__.py
index 8b137891..9d48db4f 100644
--- a/optuna_dashboard/preferential/samplers/__init__.py
+++ b/optuna_dashboard/preferential/samplers/__init__.py
@@ -1 +1 @@
-
+from __future__ import annotations