Library exports

In Webpack, it's possible to use [output.library.export](https://webpack.js.org/configuration/output/#outputlibraryexport) to choose the export of the namespace object that will be exposed as a library. For example, if my file is

```typescript
export function namedExport(): string {
return "namedExport";
}

export default function defaultExport(): string {
return "defaultExport";
}
```

I can add
```
library: {
name: 'MyLibrary',
type: 'var',
export: 'default',
},
```

and my bundle will not include the named export. Is there something similar that can be done in esbuild with the `iife` format?