New Pharo Collections: Question about MultiDictionary

Greetings to everyone. Recently i started my pre-bachelor's work called "New Collections for Pharo". (introduction to my project)
I decided to start with the MultiDictionary. There is a very basic prototype available on my project page on smalltalkhub

You can also read my post about this implementation on PillarHub.

At this point, i need your help, users and developers of Pharo! Feel free to make your suggestions about functionality of MultiDictionary that you need. Also, I'll really appreciate your suggestions about code style and in programming with Pharo in general. Thank you and best wishes.