Each of the following two procedures defines a method for adding two positive integers in terms of the procedures
inc, which increments its argument by 1, and
dec, which decrements its argument by 1.
(define (+ a b) (if (= a 0) b (inc (+ (dec a) b)))) (define (+ a b) (if (= a 0) b (+ (dec a) (inc b))))
Using the substitution model, illustrate the process generated by each procedure in evaluating
(+ 4 5). Are these processes iterative or recursive?