diff --git a/src/ruptures/costs/costgfssl2.py b/src/ruptures/costs/costgfssl2.py
index 676db61a..c9b6adc9 100644
--- a/src/ruptures/costs/costgfssl2.py
+++ b/src/ruptures/costs/costgfssl2.py
@@ -88,7 +88,6 @@ def error(self, start, end):
         return np.sum(sub_square_sum - (sub_sum**2) / (end - start))
 
 
-
 # %%
 
 # %%