Chez Scheme Transcript [Tue Mar 15 14:15:05 2011]
> (and #t #f)
#f
> (and #f #t)
#f
> (and #t #t)
#t
> (define and
    (lambda (x y)
      (if x
          y
          #f)))
> (and #f #t)
#f
> (and #t #t)
#t
> (and #t #f)
#f
> (and 3 4)
4
> (and #f #f)
#f
> (and (set! a 3) (set! b 4))
> (and (begin (set! a 3) #f) (begin (set! b 77) #t))
#f
> b
77
> (transcript-off)