3. (20%) Consider the following Scheme program: (define (mystery W) (cond ((number? W) () - vo ((number? (car W)) (cdr W)) (else (cons (mystery (car W)) (cdr W))) )) Note that number? is a built-in predicate that returns true if its argument is a number and false otherwise. * 1 liter in a la 76 % Do tej a. b. (6%) What does the above Scheme function x do? (14%) What is the result of the following calls: (mystery ((98 (2 4) (4 5) 2) (mystery (((5 3) (8)) (4))) a X