3.67

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;3.67(define (pairs s t)  (cons-stream   (list (stream-car s) (stream-car t))   (interleaves    (interleaves     (stream-map (lambda (x) (list (stream-car s) x)) (stream-cdr t))     (stream-map (lambda (x) (list x (stream-car t))) (stream-cdr s)))    (pairs (stream-cdr s) (stream-cdr t)))))