async def METHOD_NAME(event: events.CallbackQuery.Event, *_, **__):  # callback data: set_lang={lang_code}
    lang, _ = parse_callback_data_with_page(event.data)
    welcome_msg = i18n[lang]['welcome_prompt']
    await db.User.update_or_create(defaults={'lang': lang}, id=event.chat_id)
    await set_bot_commands(scope=types.BotCommandScopePeer(await event.get_input_chat()),
                           lang_code='',
                           commands=get_commands_list(lang=lang, manager=event.chat_id == env.MANAGER))
    logger.info(f'Changed language to {lang} for {event.chat_id}')
    help_button = Button.inline(text=i18n[lang]['cmd_description_help'], data='help')
    await event.edit(welcome_msg, buttons=help_button)