code: def test_clustering_directed_large(self):
      g = Graph.Ring(50, directed=True)
      clu = VertexClustering(g, [0] * 3 + [1] * 17 + [2] * 30)
      layout = [(x * 2.5, y * 2.5) for x, y in g.layout("circle")]
      plot(
          clu,
          backend="cairo",
          layout=layout,
          target=result_image_folder / "clustering_directed_large.png",
          mark_groups=True,
      )
  
imports: import random
  import unittest
  from igraph import Graph, plot, VertexClustering
label_desc: Use image node_id 4 for calling the ClusteringTestRunner obj's underlying member method code with example usage: obj.test_clustering_directed_large() without return types