(begin
  (define (newline) (display "\n"))
  (display (or #t #f)) (newline)
  (display (and #t #f)) (newline)
  (display (not #f)) (newline)
  (define a 5)
  (define (fib n)
    (cond
      ((< n 0) (display "WARNING: n smaller than 0"))
      ((< n 3) 1)
      (else (+ (fib (- n 2)) (fib (- n 1))))))
  (define (fac n) (if (= n 1) 1 (* n (fac (- n 1)))))
  (set! a (+ a a))
  (define l (list a (* 3 3) (+ a a)))
  (begin
    (display "(fac ") (display a)
    (display ") -> ") (display (fac a)) (display "\n"))
  (begin
    (display "(fib ") (display a)
    (display ") -> ") (display (fib a)) (display "\n"))
  (define l (cons 'a l))
  (display l) (newline)
  (display (cons 'a 'b)) (newline)
  (display (car l)) (newline)
  (display (cdr (cdr l))) (newline)
  (display (pair? l)) (newline)
  (display (pair? 'a)) (newline)
  (display ((lambda (x y) (* x a)) 3 5)) (newline)
  (display
    (let ((a (+ a a))
          (b (* a a))
          (x 42))
      (+ a b x)))
  (newline)
  (define (p)
    (define a 42)
    (define (f) a)
    f)
  (display ((p))) ; should return 42
  (newline)
  'done
  )