Simply Scheme Exercise 4.4 (p. 54): Each of the following procedure definitions has an error of some kind. Say what's wrong and why, and fix it. (define (sphere-volume r) (* (/ 4 3) 3.1415926535) (* r r r)) (define (next x) (x + 1)) (define (square) (* x x)) (define (triangle-area triangle) (* 0.5 base height)) (define (sum-or-squares (square x) (square y)) (+ (square x) (square y)))