code: def test_wikipedia_graph(self):
      edges1 = [
          (1, 5),
          (1, 2),
          (1, 4),
          (3, 2),
          (6, 2),
          (3, 4),
          (7, 3),
          (4, 8),
          (5, 8),
          (6, 5),
          (6, 7),
          (7, 8),
      ]
      mapped = {
          1: "a",
          2: "h",
          3: "d",
          4: "i",
          5: "g",
          6: "b",
          7: "j",
          8: "c",
      }
  
      G1 = nx.DiGraph(edges1)
      G2 = nx.relabel_nodes(G1, mapped)
  
      assert vf2pp_isomorphism(G1, G2) == mapped
  
      # Change the direction of an edge
      G1.remove_edge(1, 5)
      G1.add_edge(5, 1)
      assert vf2pp_isomorphism(G1, G2) is None
  
imports: import itertools
  import pytest
  import networkx
  from networkx import vf2pp_is_isomorphic, vf2pp_isomorphism
label_desc: Use image node_id 1 for calling the TestDiGraphISOVF2pp obj's underlying member method code with example usage: obj.test_wikipedia_graph() without return types