async def METHOD_NAME(self, request):
    # update cache on a set interval or map change or initialization
    if (self.cached_overview is None or
            self.last_map_name != self.current_map or
            time.time() - self.last_update > interval_option.get()):
        self.update_cached_overview()
    return web.Response(body=self.cached_overview,
                        content_type='image/png')