What does this program print?

Trace the program the way the computer would, then make your call before running anything.

const sky = { clouds: 5 };
const handler = {
  get(target, prop) {
    return prop in target ? target[prop] * 2 : 0;
  }
};
const proxy = new Proxy(sky, handler);
console.log(proxy.clouds + proxy.stars);