Fix formatting in handle_message docstring for consistency

app.py

@@ -7,16 +7,17 @@ from utils import generate_response
 
 def handle_message(persona, user_input, history):
     """Process a chat message and return updated history.
-    
+
     Args:
         persona: Selected chat persona
         user_input: User's message
         history: Previous chat messages
-        
+
     Returns:
         Updated chat history with new messages
     """
     # Validate inputs
+
     if not persona or persona not in PERSONAS:
         return history + [
             {"role": "assistant", "content": "Please select a valid persona"}