diff --git a/src/nested_pandas/utils/utils.py b/src/nested_pandas/utils/utils.py
index ea17ce1..e337dcf 100644
--- a/src/nested_pandas/utils/utils.py
+++ b/src/nested_pandas/utils/utils.py
@@ -29,9 +29,7 @@ def count_nested(df, nested, by=None, join=True) -> NestedFrame:
 
     if by is None:
         field_to_len = df[nested].nest.fields[0]
-        counts = (
-            df[nested].nest.to_lists().apply(lambda x: len(x[field_to_len]), axis=1)
-        )
+        counts = df[nested].nest.to_lists().apply(lambda x: len(x[field_to_len]), axis=1)
         counts.name = f"n_{nested}"  # update name directly (rename causes issues downstream)
     else:
         # this may be able to be sped up using tolists() as well