Problem 3.1: Factorials (100 pts)

For this problem, you may use the naturals stream in addition to combine-with defined above. We highly recommend you do not define any other helper functions. Such problems are likely to appear on final exam.

Write factorials, which is a stream where the nth term represents $n!$.

(define factorials
  'YOUR-CODE-HERE
)

;;; Tests
; scm> (slice factorials 0 10)
; (1 1 2 6 24 120 720 5040 40320 362880)