memory management of all_visible_functions return

[Robert E. Griffith]

I am calling all_visible_functions() in my loadable builtin. When I am 
done with the SHELL_VAR** it returns, should I xfree() it?

The reason I am asking is I followed the two places its called in the 
code and I don't see it being freed. They are pretty complicated so I 
could just be missing it but I thought I would ask. I believe that the 
returned variable is allocated in vlist_alloc() in variables.c.

And while I am asking, what is the concept of invisible variables and 
functions? Do they correspond to something we see in BASH scripts or is 
it an optimization detail?

Thanks,

--BobG