public static DirectedGraph <int> CreateSampleGraph()
        {
            var builder = new DirectedGraphBuilder <int>();

            builder.AddEdge(0, 1);
            builder.AddEdge(0, 2);
            builder.AddEdge(1, 3);
            builder.AddEdge(2, 4);

            var graph = builder.AsDirectedGraph();

            return(graph);
        }