Typescript types?

Its a bit difficult to write a definition file... any ideas how to handle that?

Would be easier if the export was the factory function that returns the exported functions:

```js
export default function worker() {
function expensive(time) {
let start = Date.now(), count = 0
while (Date.now() - start < time) count++
return count
}
return {expensive}
}
```

then the types would be identical if the functions return promises.

No files, tests, or entry points are named. Start by reviewing the 16-comment discussion and the current workerize-loader export behavior, then clarify whether the goal is a TypeScript definition file, a factory-function export, or both; done requires an agreed API and corresponding typings.

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