code: def setup_class(cls):
      cls.G1 = nx.Graph()
      cls.G2 = nx.Graph()
      cls.G3 = nx.Graph()
      cls.G4 = nx.Graph()
      cls.G5 = nx.Graph()
      cls.G6 = nx.Graph()
      cls.G1.add_edges_from([[1, 2], [1, 3], [1, 5], [2, 3]])
      cls.G2.add_edges_from([[10, 20], [20, 30], [10, 30], [10, 50]])
      cls.G3.add_edges_from([[1, 2], [1, 3], [1, 5], [2, 5]])
      cls.G4.add_edges_from([[1, 2], [1, 3], [1, 5], [2, 4]])
      cls.G5.add_edges_from([[1, 2], [1, 3]])
      cls.G6.add_edges_from(
          [[10, 20], [20, 30], [10, 30], [10, 50], [20, 50]]
      )
  
file_path: networkx/networkx/algorithms/isomorphism/tests/test_isomorphism.py
imports: import pytest
  import networkx
  from networkx.algorithms import isomorphism
label_desc: Use image node_id 1 for calling the TestIsomorph obj's underlying member method code with example usage: obj.setup_class(cls) without return types