diff --git a/src/gfn/containers/replay_buffer.py b/src/gfn/containers/replay_buffer.py
index 880314ea..c1679d9a 100644
--- a/src/gfn/containers/replay_buffer.py
+++ b/src/gfn/containers/replay_buffer.py
@@ -1,9 +1,10 @@
 from __future__ import annotations
 
 import os
-import torch
 from typing import TYPE_CHECKING, Literal
 
+import torch
+
 from gfn.containers.trajectories import Trajectories
 from gfn.containers.transitions import Transitions
 
diff --git a/src/gfn/env.py b/src/gfn/env.py
index 9b045ca3..d52306f6 100644
--- a/src/gfn/env.py
+++ b/src/gfn/env.py
@@ -389,7 +389,7 @@ class DiscreteEnvStates(DiscreteStates):
 
     def make_actions_class(self) -> type[Actions]:
         env = self
-        n_actions = self.n_actions
+        self.n_actions
 
         class DiscreteEnvActions(Actions):
             action_shape = env.action_shape
diff --git a/src/gfn/states.py b/src/gfn/states.py
index 38323abe..d7027873 100644
--- a/src/gfn/states.py
+++ b/src/gfn/states.py
@@ -1,6 +1,6 @@
 from __future__ import annotations  # This allows to use the class name in type hints
 
-from abc import ABC, abstractmethod
+from abc import ABC
 from copy import deepcopy
 from math import prod
 from typing import Callable, ClassVar, Optional, Sequence, cast
diff --git a/testing/test_environments.py b/testing/test_environments.py
index b110baac..5dbd4cc6 100644
--- a/testing/test_environments.py
+++ b/testing/test_environments.py
@@ -209,7 +209,9 @@ def test_box_fwd_step(delta: float):
     ]
 
     for failing_actions_list in failing_actions_lists_at_s0:
-        actions = env.actions_from_tensor(format_tensor(failing_actions_list, discrete=False))
+        actions = env.actions_from_tensor(
+            format_tensor(failing_actions_list, discrete=False)
+        )
         with pytest.raises(NonValidActionsError):
             states = env._step(states, actions)