useful when creating the Stow'ed variable.
When you ->get a Stow variable, you get a reference if you've
stowed an array or hash. So when you modify what you got, it
changes the original inside Stow and you don't need to do a ->set.
This wouldn't work for scalars, unless it was a scalar reference.
This also means that if you modify the variable you stowed (and you
stowed a reference) after you stowed it then the stow will change
as well.
