You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: futures.rs
    path of file: ./repos/boa/examples/src/bin
    
    the code of the file until where you have to start completion: use std::{
    cell::{Cell, RefCell},
  
    
fn add_runtime(context: &mut Context) {
    // First add the `console` object, to be able to call `console.log()`.
    let console = Console::init(context);
    context
        .register_global_property(js_string!(Console::NAME), console, Attribute::all())
        .expect("the console builtin shouldn't exist");

    // Then, bind the defined async function to the ECMAScript function "delay".
    context
        .register_global_builtin_callable(
            js_string!("delay"),
            1,
            NativeFunction::from_async_fn(delay),
        )
        .expect("the delay builtin shouldn't exist");
}