async def build_platform(self, cls: Type[Platform], custom_id):
        """
        Build the Facebook platform. Nothing fancy.
        """

        from bernard.server.http import router

        p = cls()

        if custom_id:
            p._id = custom_id

        await p.async_init()
        p.on_message(self.fsm.handle_message)
        p.hook_up(router)
        return p