A more advanced Depth First Search traversal. The vertex to start the search at Action to perform when a vertex is first encountered. Action to perform when all edges out of a vertex has been handles. Action to perform as an edge is traversed. <param
(V start, Action<V> beforevertex, Action<V> aftervertex,
Action<Edge<V, E>> onfollow, Action<Edge<V, E>> onfollowed, Action<Edge<V, E>> onnotfollowed)
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