I assume we can use something like `{ for (elem in this) elem else defaultValue }` which will be for sure more readable.

But I wasn't sure it was doing a lazy iteration on `this` and I didn't found doc to confirm it.
Well I found #488 but reading the issue It seems that it will ensure a lazy iteration for comprehensions but I'm not 100% sure about it.

If you can confirm it, I will change for a comprehension.