Update app.py

app.py

@@ -81,7 +81,7 @@ def Assistant(
             tokens.extend(message_tokens)
 
     last_user_message = history[-1][0]
-    message_tokens = get_message_tokens(model=model, role="User", content=last_User_message,)
+    message_tokens = get_message_tokens(model=model, role="User", content=last_user_message,)
     tokens.extend(message_tokens)
 
     role_tokens = [model.token_bos(), BOT_TOKEN, LINEBREAK_TOKEN]