[Pharo-users] Multiple sorting helper

Hi, I have a collection of objects and I want to sort its contents by more than one attribute (including nil values), and I thought somebody might have already done this. Something like: sorter := MultipleSortCriteria new add: #lastName; add: [:each | each personalInfo age ] ascending: false. aCollection asSortedCollection: sorter. Is there a package with utility classes for this? Thank you! Esteban A. Maringolo