Is there a way to load external scripts / other libraries 

I would like to make a test with `p5.xr` among other libraries. Is there an `official` way to do this?

I'm thinking of doing something like this if not
```js
function addScript(src) {
  const script = document.createElement('script');
  script.src = src;
  document.head.appendChild(script);
}

addScript("path/to/your/script.js");
```