How to call pubsub in an example() in the controls-galley

[dsandms]

I am a newbie and trying to setup a chat example in the controls-gallery example. Any help would be appreciated. I am stuck at the pubsub call. Since its accesible as page.pubsub but since page is directly not callable in the example()

Here is my code

import asyncio
import flet as ft
name = "Chat example"

def example():
# subscribe to broadcast messages
def send_click(e):
print("reached here")
e.control.page.pubsub.send_all(f"{user.value}: {message.value}")
# clean up the form
message.value = ""
def on_message(msg):
messages.controls.append(ft.Text(msg))
page.update() # this is where its going wrong
page.pubsub.subscribe(on_message) # this is where its going wrong
messages = ft.Column()
user = ft.TextField(hint_text="Your name", width=150)
message = ft.TextField(hint_text="Your message...", width=150) # fill all the space
send = ft.ElevatedButton("Send", on_click=send_click)
row0 = ft.Row([user, message, send],wrap=True)

return ft.Column(controls=[messages, row0])