;; Defining a Directed Graph

(define dg (digraph '(1 2 3 4 5 6) '((1 2) (1 4) (2 5) (3 5) (3 6) (4 2)(5 4))))

(define gv (make <graph-view> :graph dg :layout 'custom)) 

(describe (out-neighbors (vertex-ref dg 0)))  ; the vertices to which
					      ; the first vertex ("1") points
