I'm rusty but I wanted to share something 

I did 

MooseModel allInstances second allModelClasses numberOfLinesOfCode

and I got an error because a group does not know number of lines of code.

Why a FamixClassGroup does not know this message?

In fact it knows totalNumberOfLinesOfCode

But numberOfLinesOfCode is defined on model.

So is there a way to convert a group into a model?

Stef