diff --git a/graphene_django/rest_framework/serializer_converter.py b/graphene_django/rest_framework/serializer_converter.py
index 35c8dc8..c419419 100644
--- a/graphene_django/rest_framework/serializer_converter.py
+++ b/graphene_django/rest_framework/serializer_converter.py
@@ -57,7 +57,9 @@ def convert_serializer_field(field, is_input=True):
 
 
 def convert_serializer_to_input_type(serializer_class):
-    cached_type = convert_serializer_to_input_type.cache.get(serializer_class.__name__, None)
+    cached_type = convert_serializer_to_input_type.cache.get(
+        serializer_class.__name__, None
+    )
     if cached_type:
         return cached_type
     serializer = serializer_class()
diff --git a/graphene_django/rest_framework/tests/test_multiple_model_serializers.py b/graphene_django/rest_framework/tests/test_multiple_model_serializers.py
index 4504610..c1f4626 100644
--- a/graphene_django/rest_framework/tests/test_multiple_model_serializers.py
+++ b/graphene_django/rest_framework/tests/test_multiple_model_serializers.py
@@ -18,8 +18,12 @@ class MyFakeChildModel(models.Model):
 class MyFakeParentModel(models.Model):
     name = models.CharField(max_length=50)
     created = models.DateTimeField(auto_now_add=True)
-    child1 = models.OneToOneField(MyFakeChildModel, related_name='parent1', on_delete=models.CASCADE)
-    child2 = models.OneToOneField(MyFakeChildModel, related_name='parent2', on_delete=models.CASCADE)
+    child1 = models.OneToOneField(
+        MyFakeChildModel, related_name="parent1", on_delete=models.CASCADE
+    )
+    child2 = models.OneToOneField(
+        MyFakeChildModel, related_name="parent2", on_delete=models.CASCADE
+    )
 
 
 class ParentType(DjangoObjectType):