(define repeat-and-double-each-number1
   (lambda (l)
      (cond ((null? l) null)
            (else      (cons (* 2 (car l))
                             (cons (* 2 (car l))
                                   (repeat-and-double-each-number1 (cdr l))))))))

(define double (lambda (n) (* 2 n)))
(define repeat-and-double-each-number2
   (lambda (l)
      (cond ((null? l) null)
            (else      (cons (double (car l))
                             (cons (double (car l))
                                   (repeat-and-double-each-number2 (cdr l))))))))

(define double-first-element (lambda (ll) (* 2 (car ll))))
(define repeat-and-double-each-number3
   (lambda (l)
      (cond ((null? l) null)
            (else      (cons (double-first-element l)
                             (cons (double-first-element l)
                                   (repeat-and-double-each-number3 (cdr l))))))))

(define repeat-first-element
   (lambda (n ll)
       (cons n (cons n ll))))
(define repeat-and-double-each-number4
   (lambda (l)
      (cond ((null? l) null)
            (else      (repeat-first-element
                          (* 2 (car l))
                          (repeat-and-double-each-number4 (cdr l)))))))

;(define repeat-and-double-each-number5
;   (lambda (l)
;      (cond ((null? l) null)
;            (else      ((lambda (n ll) (cons n (cons n ll)))
;                        (* 2 (car l))
;                        (repeat-and-double-each-number5 (cdr l)))))))

(define repeat-and-double-each-number6
   (lambda (l)
      (cond ((null? l) null)
            (else      (local [(define n (* 2 (car l)))
                               (define ll (repeat-and-double-each-number6 (cdr l)))]
                          (cons n (cons n ll)))))))

(define repeat-and-double-each-number7
   (lambda (l)
      (local ((define n (* 2 (car l)))
              (define ll (repeat-and-double-each-number7 (cdr l))))
         (cond ((null? l) null)
               (else (cons n (cons n ll)))))))

(define double-even-numbers
    (lambda (l)
        (cond ((null? l) null)
              (else (local [(x (double-even-numbers (cdr l)))]
                       (cond ((even? (car l)) (cons (double (car l)) x))
                             ((odd? (car l)) (cons (car l) x))))))))

(define max-list1
    (lambda (l)
        (cond ((null? l) 0)
              (else (if (> (car l) (max-list1 (cdr l)))
                        (car l)
                        (max-list1 (cdr l)))))))

(define max-list2
    (lambda (l)
        (cond ((null? l) 0)
              (else (local [(define m (max-list2 (cdr l)))]
                       (if (> (car l) m)
                           (car l)
                           m))))))