bn: Remove some extra module code at the bottom.

bn.rkt

@@ -85,9 +85,3 @@
 (: make-bn-forms (-> (Listof (Pairof Variable UpdateFuncForm)) Network))
 (define (make-bn-forms forms)
   (bn-form->bn (make-hash forms)))
-
-(let ([bn (make-bn-forms '((a . (and a b))
-                           (b . (not b))))]
-      [s (make-state '((a . #t)
-                       (b . #t)))])
-  ((hash-ref bn 'a) s))