#lang scheme
(define (sm symbol)
  (lambda (frag) (
                  (call/cc (lambda (ret) (
                                          (call/cc (lambda (k) (
                                                                (ret (and (eq? (car frag) symbol) (cons (cdr frag) k)))
                                                                )))
                                          (ret #f)
                                          )))
                  )
    )
  )