I need to map from a `string` (or `ArrayBuffer`, if that's easier) to a `ReadableStream<Uint8Array>`. This is in a NodeJS environment. How is this done? Most digging I've done shows something like:

```
import { Readable } from "stream";

Readable.from("foo");

```

But `Readable.from` returns a `Readable`, and I need a `ReadableStream<Uint8Array>`.

I'd like to be able to do something like:

```
const stream = ReadableStream.from("foo");

```