Anyone interested in "package versioning"?

Hi CL Pros, I just came across a post on Quora <https://www.quora.com/Where-did-we-go-wrong-Why-didnt-Common-Lisp-fix-the-world/answer/Robert-Smith-9?srid=dnzK> by Robert Smith where he mentions the idea of assigning some sort of "version" to Common Lisp packages in order to improve code configuration control. This seems to me to be a pretty neat and interesting idea! Has anyone of you explored such a concept, or know of anyone that did? Or, is anyone of you curious about it? I think pretty seriously that I will implement something like this as a CL extension in my upcoming MKCL 2.0. Cheers, Jean-Claude Beaudoin