code: def setup_class(cls):
      cls.P3 = nx.path_graph(3)
      cls.P4 = nx.path_graph(4)
      cls.K5 = nx.complete_graph(5)
  
      cls.C4 = nx.cycle_graph(4)
      cls.C4_directed = nx.cycle_graph(4, create_using=nx.DiGraph)
  
      cls.C5 = nx.cycle_graph(5)
  
      cls.T = nx.balanced_tree(r=2, h=2)
  
      cls.Gb = nx.DiGraph()
      cls.Gb.add_edges_from(
          [(0, 1), (0, 2), (0, 4), (2, 1), (2, 3), (4, 3)]
      )
  
file_path: networkx/networkx/algorithms/centrality/tests/test_harmonic_centrality.py
imports: import pytest
  import networkx
  from networkx.algorithms.centrality import harmonic_centrality
label_desc: Use image node_id 1 for calling the TestClosenessCentrality obj's underlying member method code with example usage: obj.setup_class(cls) without return types