fix black + PR comments.

Author: nadiaya

src/sagemaker/user_agent.py

@@ -29,7 +29,7 @@
 )
 
 
-def determine_prefix(user_agent):
+def determine_prefix(user_agent=""):
     """Placeholder docstring"""
     prefix = "AWS-SageMaker-Python-SDK/{}".format(SDK_VERSION)
 
@@ -56,7 +56,7 @@ def prepend_user_agent(client):
     Args:
         client:
     """
-    prefix = determine_prefix(client._client_config.user_agent or "")
+    prefix = determine_prefix(client._client_config.user_agent)
 
     if client._client_config.user_agent is None:
         client._client_config.user_agent = prefix

tests/unit/test_endpoint_from_job.py

@@ -43,7 +43,9 @@
 @pytest.fixture()
 def sagemaker_session():
     boto_mock = MagicMock(name="boto_session", region_name=REGION)
-    ims = sagemaker.Session(sagemaker_client=MagicMock(name="sagemaker_client"), boto_session=boto_mock)
+    ims = sagemaker.Session(
+        sagemaker_client=MagicMock(name="sagemaker_client"), boto_session=boto_mock
+    )
     ims.sagemaker_client.describe_training_job = Mock(
         name="describe_training_job", return_value=TRAINING_JOB_RESPONSE
     )

tests/unit/test_endpoint_from_model_data.py

@@ -36,7 +36,9 @@
 @pytest.fixture()
 def sagemaker_session():
     boto_mock = MagicMock(name="boto_session", region_name=REGION)
-    ims = sagemaker.Session(sagemaker_client=MagicMock(name="sagemaker_client"), boto_session=boto_mock)
+    ims = sagemaker.Session(
+        sagemaker_client=MagicMock(name="sagemaker_client"), boto_session=boto_mock
+    )
     ims.sagemaker_client.describe_model = Mock(
         name="describe_model", side_effect=_raise_does_not_exist_client_error
     )