document ContainerBlot?

[cellog]

I was trying to add a columns blot, which would allow specifying 1-3 columns. The closest analog I can find is the list, used in Quill for <ol>/<ul>. However, it is 100% undocumented, and after 3 hours of fiddling, I still have absolutely no idea how it is supposed to work. This is going to force me to give up on Quill, because I am trying to write an extensible editor that other devs can use to add their own modules. If I can't figure it out from the source, there is a 0% chance that they will be able to.

So, this is more a plea for future devs:

Would someone who knows how ContainerBlot works be so kind as to update the documentation?