added qa part

app.py

@@ -62,8 +62,8 @@ def load_files(file_path: str):
 # Respond function
 def respond(message, history):
     # Use the preloaded LLM
-    query_engine = vector_index.as_chat_engine(llm=llm)
-    streaming_response = query_engine.stream_chat(message)
+    query_engine = vector_index.as_query_engine(streaming=True, llm=llm)
+    streaming_response = query_engine.query(message)
     partial_text = ""
     for new_text in streaming_response.response_gen:
         partial_text += new_text
@@ -71,6 +71,13 @@ def respond(message, history):
         yield partial_text
 
 
+# Clear function
+def clear_state():
+    global vector_index
+    vector_index = None
+    return [None, None, None]
+
+
 # UI Setup
 with gr.Blocks(
     theme=gr.themes.Default(
@@ -105,7 +112,7 @@ with gr.Blocks(
     # Set up Gradio interactions
     btn.click(fn=load_files, inputs=file_input, outputs=output)
     clear.click(
-        lambda: [None, None],
+        fn=clear_state,  # Use the clear_state function
         outputs=[file_input, output],
     )