diff --git a/moto/cognitoidp/models.py b/moto/cognitoidp/models.py
index 082fa5189..b67239e93 100644
--- a/moto/cognitoidp/models.py
+++ b/moto/cognitoidp/models.py
@@ -108,7 +108,9 @@ class CognitoIdpUserPool(BaseModel):
 
         return user_pool_json
 
-    def create_jwt(self, client_id, username, token_use, expires_in=60 * 60, extra_data={}):
+    def create_jwt(
+        self, client_id, username, token_use, expires_in=60 * 60, extra_data={}
+    ):
         now = int(time.time())
         payload = {
             "iss": "https://cognito-idp.{}.amazonaws.com/{}".format(
diff --git a/tests/test_cognitoidp/test_cognitoidp.py b/tests/test_cognitoidp/test_cognitoidp.py
index 71a6e3191..79e6dbbb8 100644
--- a/tests/test_cognitoidp/test_cognitoidp.py
+++ b/tests/test_cognitoidp/test_cognitoidp.py
@@ -1150,6 +1150,7 @@ def test_token_legitimacy():
         access_claims[k].should.equal(v)
     access_claims["token_use"].should.equal("access")
 
+
 @mock_cognitoidp
 def test_change_password():
     conn = boto3.client("cognito-idp", "us-west-2")