$ cat crazy.scm
(let ((a 1))
  (define (f x)
    (define b (+ a x))
    (define a 5)
    (+ a b))
  (print (f 10)))


$ csc crazy.scm

$ ./crazy
20

$ cat crazy2.scm
(let ((a 1))
  (define (f x)
    (define b (+ a x))
    (print "b=" b)
    (define a 5)
    (print "a=" a)
    (+ a b))
  (print (f 10)))

$ csc crazy2.scm

$ ./crazy2
b=11
a=5
16