Digraph not accurate

[handav]

I've been trying to work with the EdgeWeightedDigraph, but the number of edges and particularly the vertexes are consistently wrong. With the example code in the README (below), printing digraph.v() and digraph.e() gives me 7 and 6, respectively. The README says they should both be 5, but I would imagine they should both be 6, as there are 6 vertexes and 6 edges. Any direction would be helpful.

var EdgeWeightedDigraph = natural.EdgeWeightedDigraph;
var digraph = new EdgeWeightedDigraph();
digraph.add(5,4,0.35);
digraph.add(5,1,0.32);
digraph.add(1,3,0.29);
digraph.add(6,2,0.40);
digraph.add(3,6,0.52);
digraph.add(6,4,0.93);