Generic stream-map

Complete the following definition, which generalizes stream-map to allow procedures that take multiple arguments, analogous to Scheme standart map . Scheme standardly provides a generic map procedure. This more general map takes a procedure of n arguments, together with n lists, and applies the procedure to all the first elements of the lists, all the second elements of the lists, and so on, returning a list of the results. For example:

(map + (list 1 2 3) (list 40 50 60) (list 700 800 900))
(741 852 963)

(map (lambda (x y) (+ x (* 2 y)))
     (list 1 2 3)
     (list 4 5 6))
(9 12 15)


(define (stream-map proc . argstreams)
  (if (<??> (car argstreams))
      the-empty-stream
      (<??>
       (apply proc (map <??> argstreams))
       (apply stream-map
              (cons proc (map <??> argstreams))))))

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