clear till index - bug fixes

app.py

@@ -1,10 +1,10 @@
 import gradio as gr
 
 
-def get_model_response(chat_txt, user_chats, full_chat_history):
-    response = f'Hello, you said "{chat_txt}"'
-    full_chat_history = full_chat_history + [chat_txt, response]
-    user_chats.append(chat_txt)
+def get_model_response(txt: str, user_chats: list[str], full_chat_history: list[str]):
+    response = f'Hello, you said "{txt}"'
+    full_chat_history = full_chat_history + [txt, response]
+    user_chats.append(txt)
     responses = [
         (full_chat_history[i], full_chat_history[i + 1])
         for i in range(0, len(full_chat_history) - 1, 2)
@@ -13,11 +13,19 @@ def get_model_response(chat_txt, user_chats, full_chat_history):
 
 
 def clear_chat(
-    full_chat_history, chatbox, user_chats, cleartill_dropdown_choices, drop_down
+    full_chat_history: list[str],
+    chatbox: list[tuple[str, str]],
+    user_chats: list[str],
+    cleartill_dropdown_choices: list[str],
+    drop_down: str,
 ):
-    index = user_chats.index(drop_down)
+    if drop_down == "":
+        index = 0
+    else:
+        index = user_chats.index(drop_down)
     return (
-        full_chat_history[:index],
+        # full_chat_history has user_chat and response chats in a single line.
+        full_chat_history[: index * 2],
         chatbox[:index],
         user_chats[:index],
         cleartill_dropdown_choices[:index],