diff --git a/graphene_django/rest_framework/mutation.py b/graphene_django/rest_framework/mutation.py
index e2b9e4b..b7393da 100644
--- a/graphene_django/rest_framework/mutation.py
+++ b/graphene_django/rest_framework/mutation.py
@@ -39,7 +39,9 @@ def fields_for_serializer(
                 field.read_only
                 and is_input
                 and lookup_field != name,  # don't show read_only fields in Input
-                isinstance(field, serializers.HiddenField),  # don't show hidden fields in Input
+                isinstance(
+                    field, serializers.HiddenField
+                ),  # don't show hidden fields in Input
             ]
         )