Remi-Leblond/S99 — comment on commit 5476124d708c40b1574dbf0b4322103a86979b91
File: src/S1.scala line 18
By LannyRipple:

You'd usually handle argument requirements with the require() function

```scala
require(l.nonEmpty, "empty list")
```

If the first argument evaluates to false then you get an IllegalArgumentException with the second argument as an explanation.