(define (root msg)
  (let ([slots (make-hash)])
    (hash-set! slots 'responds-to (λ() (hash-keys slots)))
    (hash-set! slots 'make-slot (λ (key value) (hash-set! slots key value)))

    (hash-set! slots 'clone
               (λ(msg) (let ([slots (hash-copy slots)]) (hash-ref slots msg))))

    (hash-ref slots msg)))