code: def setup_class(cls):
      cls.G = nx.Graph(name="test")
      e = [
          ("a", "b"),
          ("b", "c"),
          ("c", "d"),
          ("d", "e"),
          ("e", "f"),
          ("a", "f"),
      ]
      cls.G.add_edges_from(e)
      cls.G.add_node("g")
      cls.DG = nx.DiGraph(cls.G)
      cls.XG = nx.MultiGraph()
      cls.XG.add_weighted_edges_from(
          [(1, 2, 5), (1, 2, 5), (1, 2, 1), (3, 3, 42)]
      )
      cls.XDG = nx.MultiDiGraph(cls.XG)
  
imports: import io
  import pytest
  import networkx
  from networkx.utils import edges_equal, graphs_equal, nodes_equal
label_desc: Use image node_id 1 for calling the TestAdjlist obj's underlying member method code with example usage: obj.setup_class(cls) without return types