FragmentFrom

    FragmentFrom(vertices)
    {
        // Create a new graph with only the desired vertices.
        const g = new ServiceGraph(); // TODO: In the super class it's just `new Graph()` ...

        _.each(vertices, (vertex) =>
        {
            g.AddVertex(_.cloneDeep(vertex));
        });

        // Prune edges with missing vertices.
        g._prune();

        return g;
    }