I'm using dynamic imports with Angular 7 to reduce the size of the initial vendor bundle.

```
import('xlsx').then(XLSX => {
    const wb: XLSX.WorkBook = XLSX.read(bstr, { type: 'binary' });
})

```

But there is an error on the `XLSX.WorkBook` type saying:

> 
> `Cannot find namespace XLSX.`
> 
> 
> 

`XLSX.read` works fine.

Question : How do I define types when using dynamic imports?