Update app.py

app.py

@@ -15,7 +15,9 @@ with gr.Blocks() as demo:
         textbox2 = gr.Textbox()
 
     def echo(message, chat_history):
-        return '', 'echo ' + message
+        bot_message = 'echo ' + message
+        chat_history.append((message, bot_message))
+        return '', chat_history
 
     textbox1.submit(echo, [textbox1, chatbot1], [textbox1, chatbot1])
     textbox2.submit(echo, [textbox2, chatbot2], [textbox2, chatbot2])