code: def test_triangle_and_edge(self):
      G = nx.cycle_graph(3, create_using=nx.DiGraph())
      G.add_edge(0, 4)
      assert nx.clustering(G)[0] == 1 / 6
  
imports: import pytest
  import networkx
label_desc: Use image node_id 4 for calling the TestDirectedClustering obj's underlying member method code with example usage: obj.test_triangle_and_edge() without return types