question concerning arranger tool

[Stefan Thomas]

Dear community,
I try to understand more of the arranger tool, have a look at
https://github.com/gilles-th/arranger.ly
Could someone give an instructional example, what the functions copy-out
can do and how it works?
I generally think taht there should be more examples in the docs. I'm
willing to help in this regard but therefore I sould understand a bit more
of the staff.
Thanks,
Stefan