docstr: Betweenness centrality: P4 normalized
docstr_tok: ["Betweenness","centrality",":","P4","normalized"]
code: def test_P4_normalized(self):
      """Betweenness centrality: P4 normalized"""
      G = nx.path_graph(4)
      b = nx.current_flow_betweenness_centrality(G, normalized=True)
      b_answer = {0: 0, 1: 2.0 / 3, 2: 2.0 / 3, 3: 0}
      for n in sorted(G):
          assert b[n] == pytest.approx(b_answer[n], abs=1e-7)
  
imports: import pytest
  import networkx
  from networkx import approximate_current_flow_betweenness_centrality
  from networkx import edge_current_flow_betweenness_centrality
label_desc: Use image node_id 3 for calling the TestFlowBetweennessCentrality obj's underlying member method code with example usage: obj.test_P4_normalized() without return types