diff --git a/packages/jupyter-ai/jupyter_ai/chat_handlers/base.py b/packages/jupyter-ai/jupyter_ai/chat_handlers/base.py
index ba0314c08..017f342fd 100644
--- a/packages/jupyter-ai/jupyter_ai/chat_handlers/base.py
+++ b/packages/jupyter-ai/jupyter_ai/chat_handlers/base.py
@@ -33,7 +33,9 @@ class BaseChatHandler(Configurable):
     Not necessary when the routing method is "slash_command"."""
 
     # TODO: make NotImplemented
-    help: ClassVar[str] = "This is used when the message in the chat interface is not a command"
+    help: ClassVar[
+        str
+    ] = "This is used when the message in the chat interface is not a command"
     """What this chat handler does, which third-party models it contacts,
     the format of the data it returns to the user, etc. Used in the UI."""
 
diff --git a/packages/jupyter-ai/jupyter_ai/chat_handlers/custom.py b/packages/jupyter-ai/jupyter_ai/chat_handlers/custom.py
index 2f419721a..d69b29413 100644
--- a/packages/jupyter-ai/jupyter_ai/chat_handlers/custom.py
+++ b/packages/jupyter-ai/jupyter_ai/chat_handlers/custom.py
@@ -8,6 +8,7 @@
 
 CUSTOM_MESSAGE = "This handler displays a custom message in response to any prompt."
 
+
 def CustomMessage():
     return AgentChatMessage(
         id=uuid4().hex,
@@ -16,9 +17,12 @@ def CustomMessage():
         reply_to="",
     )
 
+
 """
 This is a sample custom chat handler class to demonstrate entry points.
 """
+
+
 class CustomChatHandler(BaseChatHandler):
     id = "custom"
     name = "Custom"