docstr: Closeness centrality: K4
docstr_tok: ["Closeness","centrality",":","K4"]
code: def test_K4(self):
      """Closeness centrality: K4"""
      G = nx.complete_graph(4)
      b = nx.current_flow_closeness_centrality(G)
      b_answer = {0: 2.0 / 3, 1: 2.0 / 3, 2: 2.0 / 3, 3: 2.0 / 3}
      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 1 for calling the TestFlowClosenessCentrality obj's underlying member method code with example usage: obj.test_K4() without return types