diff --git a/src/circulation/base.py b/src/circulation/base.py
index b388345..daf3e87 100644
--- a/src/circulation/base.py
+++ b/src/circulation/base.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 from typing import Callable, Any
 from abc import ABC, abstractmethod
 import json
diff --git a/src/circulation/regazzoni2020.py b/src/circulation/regazzoni2020.py
index 372c4de..277b0da 100644
--- a/src/circulation/regazzoni2020.py
+++ b/src/circulation/regazzoni2020.py
@@ -1,5 +1,6 @@
-from typing import Callable, Any
+from __future__ import annotations
 
+from typing import Callable, Any
 
 from . import base
 from . import units
diff --git a/src/circulation/zenkur.py b/src/circulation/zenkur.py
index e585c5d..ad5b959 100644
--- a/src/circulation/zenkur.py
+++ b/src/circulation/zenkur.py
@@ -1,7 +1,5 @@
+from __future__ import annotations
 import numpy as np
-# from scipy.integrate import RK45, solve_ivp
-
-
 from . import base
 from . import units