/// <summary>
/// Takes the first n nodes, ordered ascendingly by degree.
/// </summary>
/// <typeparam name="TNode"></typeparam>
/// <param name="graph"></param>
/// <param name="n">Upper bound on the number of nodes to sample.</param>
/// <returns></returns>
public static IEnumerable <TNode> LowDegreeFirst <TNode, TLabel>(this MultiDirectedGraph <TNode, TLabel> graph, int n)
{
// Sort nodes by their degree in ascending order
TNode[] nodes = Utils.Shuffled(graph.Nodes.ToArray()).ToArray();
Array.Sort(nodes, (n1, n2) => graph.Degree(n1).CompareTo(graph.Degree(n2)));
// Take lowest degree nodes first
return(nodes.Take(Math.Min(n, graph.NumNodes)));
}