请定义一个过程，它以三个数为参数，返回其中较大的两个数之和

(define (square x (* x x))
(define (sum-of-squares x y (+ (square x) (square y)))
(define (sum-of-max-2-of-3 x y z)
  (cond (and (<= x y) (< x z)) (+ y z)
        (and (<= y x) (< y z)) (+ y z)
        (and (<= z y) (< z x)) (+ y z)
  )
)