(define stack #null)
(print "stack is: " stack)
(print "is stack empty: " (eq? stack #null))

(print "* pushing 1")
(define stack (cons 1 stack))
(print "stack is: " stack)
(print "is stack empty: " (eq? stack #null))

(print "* pushing 2")
(define stack (cons 2 stack))
(print "stack is: " stack)
(print "is stack empty: " (eq? stack #null))

(print "* pushing 3")
(define stack (cons 3 stack))
(print "stack is: " stack)
(print "is stack empty: " (eq? stack #null))

(print "* poping")
(define-values (value stack) (uncons stack #f))
(print "value: " value)
(print "stack: " stack)
(print "is stack empty: " (eq? stack #null))

(print "* poping")
(define-values (value stack) (uncons stack #f))
(print "value: " value)
(print "stack: " stack)
(print "is stack empty: " (eq? stack #null))

(print "* poping")
(define-values (value stack) (uncons stack #f))
(print "value: " value)
(print "stack: " stack)
(print "is stack empty: " (eq? stack #null))

(print "* poping")
(define-values (value stack) (uncons stack #f))
(print "value: " value)
(print "stack: " stack)
(print "is stack empty: " (eq? stack #null))