docstr: Katz centrality: K5
code: def test_K5(self):
      """Katz centrality: K5"""
      G = nx.complete_graph(5)
      alpha = 0.1
      b = nx.katz_centrality(G, alpha)
      v = math.sqrt(1 / 5.0)
      b_answer = dict.fromkeys(G, v)
      for n in sorted(G):
          assert b[n] == pytest.approx(b_answer[n], abs=1e-7)
      nstart = {n: 1 for n in G}
      b = nx.katz_centrality(G, alpha, nstart=nstart)
      for n in sorted(G):
          assert b[n] == pytest.approx(b_answer[n], abs=1e-7)
  
imports: import math
  import pytest
  import networkx
label_desc: Use image node_id 1 for calling the TestKatzCentrality obj's underlying member method code with example usage: obj.test_K5() without return types