docstr: Closeness centrality: P4
docstr_tok: ["Closeness","centrality",":","P4"]
code: def test_P4(self):
      """Closeness centrality: P4"""
      G = nx.path_graph(4)
      b = nx.current_flow_closeness_centrality(G)
      b_answer = {0: 1.0 / 6, 1: 1.0 / 4, 2: 1.0 / 4, 3: 1.0 / 6}
      for n in sorted(G):
          assert b[n] == pytest.approx(b_answer[n], abs=1e-7)
  
file_path: networkx/networkx/algorithms/centrality/tests/test_current_flow_closeness.py
imports: import pytest
  import networkx
label_desc: Use image node_id 2 for calling the TestFlowClosenessCentrality obj's underlying member method code with example usage: obj.test_P4() without return types