diff --git a/optuna_dashboard/preferential/samplers/__init__.py b/optuna_dashboard/preferential/samplers/__init__.py
index 3ec05149..f68708f4 100644
--- a/optuna_dashboard/preferential/samplers/__init__.py
+++ b/optuna_dashboard/preferential/samplers/__init__.py
@@ -2,4 +2,5 @@ from __future__ import annotations
 
 from ._gp import PreferentialGPSampler
 
-__all__ = ["PreferentialGPSampler"]
\ No newline at end of file
+
+__all__ = ["PreferentialGPSampler"]
diff --git a/optuna_dashboard/preferential/samplers/_gp.py b/optuna_dashboard/preferential/samplers/_gp.py
index c77d5dc6..706a2327 100644
--- a/optuna_dashboard/preferential/samplers/_gp.py
+++ b/optuna_dashboard/preferential/samplers/_gp.py
@@ -26,6 +26,7 @@ from optuna._transform import _SearchSpaceTransform
 from optuna.distributions import BaseDistribution
 from optuna.search_space import IntersectionSearchSpace
 from optuna.trial import FrozenTrial
+from optuna_preferential._preferences import get_preferences
 import pyro
 import pyro.infer.autoguide
 import pyro.infer.mcmc
@@ -33,8 +34,6 @@ from scipy.special import erfcinv
 import torch
 from torch import Tensor
 
-from optuna_preferential._preferences import get_preferences
-
 
 class WeightedGaussianLikelihood(GaussianLikelihood):
     def __init__(