Function fetch_the_descendants_and_link_module_script 

fn fetch_the_descendants_and_link_module_script(
    cx: &mut JSContext,
    global: &GlobalScope,
    module_script: Rc<ModuleTree>,
    fetch_client: ModuleFetchClient,
    destination: Destination,
    on_complete: impl FnOnce(&mut JSContext, Option<Rc<ModuleTree>>) + Clone + 'static,
)

https://html.spec.whatwg.org/multipage/#fetch-the-descendants-of-and-link-a-module-script