code: def test_panther_similarity_unweighted(self):
      np.random.seed(42)
  
      G = nx.Graph()
      G.add_edge(0, 1)
      G.add_edge(0, 2)
      G.add_edge(0, 3)
      G.add_edge(1, 2)
      G.add_edge(2, 4)
      expected = {3: 0.5, 2: 0.5, 1: 0.5, 4: 0.125}
      sim = nx.panther_similarity(G, 0, path_length=2)
      assert sim == expected
  
imports: import pytest
  import networkx
  from networkx.algorithms.similarity import graph_edit_distance, optimal_edit_paths, optimize_graph_edit_distance
  from networkx.generators.classic import circular_ladder_graph, cycle_graph, path_graph, wheel_graph
label_desc: Use image node_id 39 for calling the TestSimilarity obj's underlying member method code with example usage: obj.test_panther_similarity_unweighted() without return types