on Ruby one have something like this:

```
@var ||= 'value' 

```

basically, it means that `@var` will be assigned `'value'` only if `@var` is not assigned yet (e.g. if `@var` is `nil`)

I'm looking for the same on Kotlin, but so far, the closest thing would be the elvis operator. Is there something like that and I missed the documentation?