public void BreadthFirstWalk(BreadthFirstHandler handler, int root, DirectedWalkMode mode, bool includeUnreachableFromRoot = false, object tag = null)
{
igraph_bfshandler_t wrapper = (t, vid, pred, succ, rank, dist, extra) => handler != null && handler(this, vid, pred, succ, rank, dist, tag);
DllImporter.igraph_bfs(graph, root, null, (igraph_neimode_t)mode, includeUnreachableFromRoot, null, null, null, null, null, null, null, wrapper, tag);
}