diff --git a/src/gfn/gflownet/flow_matching.py b/src/gfn/gflownet/flow_matching.py
index 38072080..4d2f2354 100644
--- a/src/gfn/gflownet/flow_matching.py
+++ b/src/gfn/gflownet/flow_matching.py
@@ -203,9 +203,7 @@ def loss(
         )
         return fm_loss + self.alpha * rm_loss
 
-    def to_training_samples(
-        self, trajectories: Trajectories
-    ) -> Union[
+    def to_training_samples(self, trajectories: Trajectories) -> Union[
         Tuple[DiscreteStates, DiscreteStates, torch.Tensor, torch.Tensor],
         Tuple[DiscreteStates, DiscreteStates, None, None],
         Tuple[States, States, torch.Tensor, torch.Tensor],
diff --git a/src/gfn/samplers.py b/src/gfn/samplers.py
index eb224fbf..0df9449f 100644
--- a/src/gfn/samplers.py
+++ b/src/gfn/samplers.py
@@ -35,7 +35,11 @@ def sample_actions(
         save_estimator_outputs: bool = False,
         save_logprobs: bool = True,
         **policy_kwargs: Any,
-    ) -> Tuple[Actions, torch.Tensor | None, torch.Tensor | None,]:
+    ) -> Tuple[
+        Actions,
+        torch.Tensor | None,
+        torch.Tensor | None,
+    ]:
         """Samples actions from the given states.
 
         Args: