private void SerializeVertices(StreamWriter outfile)
{
foreach (var vertex in _graph.Vertices)
{
var inDegree = _graph.InEdges(vertex).Count();
var outDegree = _graph.OutEdges(vertex).Count();
outfile.WriteLine(String.Format(CultureInfo.InvariantCulture, " <node id=\"n{0}\" parse.indegree=\"{1}\" parse.outdegree=\"{2}\">",
vertex.VertexId, inDegree, outDegree));
SerializePropertyValues(outfile, vertex);
outfile.WriteLine(" </node>");
}
}