[yomly]

There is an exercise - 2.29 where you implement a tree-like structure of objects.

Part d of the question is:

" d. Suppose we change the representation of mobiles so that the constructors are

(define (make-mobile left right) (cons left right)) (define (make-branch length structure) (cons length structure))

How much do you need to change your programs to convert to the new representation? "

It may not be discussed in depth - I suspect they decided it was out of scope for the book, but they were definitely thinking about it...