"multi-level classification" is not documented

[2colours]

Problem or new feature

Apparently, when classify or classify-list has a tester that returns an Iterable, the individual elements of it will be considered a classification hierarchy, and hence create a nested Hash. The same is probably true for categorization as well. It probably won't go away - even though I think it's a problem that there seems to be no way around it - so it will need to be documented.

Suggestions

Rakudo source Roast example