docstr: Edge betweenness centrality: P4
docstr_tok: ["Edge","betweenness","centrality",":","P4"]
code: def test_normalized_P4(self):
      """Edge betweenness centrality: P4"""
      G = nx.path_graph(4)
      b = nx.edge_betweenness_centrality(
          G, weight=None, normalized=True
      )
      b_answer = {(0, 1): 3, (1, 2): 4, (2, 3): 3}
      for n in sorted(G.edges()):
          assert b[n] == pytest.approx(b_answer[n] / 6, abs=1e-7)
  
imports: import pytest
  import networkx
label_desc: Use image node_id 5 for calling the TestEdgeBetweennessCentrality obj's underlying member method code with example usage: obj.test_normalized_P4() without return types