code: def setup_class(cls):
      cls.P4 = nx.path_graph(4)
      cls.D = nx.DiGraph()
      cls.D.add_edges_from([(0, 2), (0, 3), (1, 3), (2, 3)])
      cls.D2 = nx.DiGraph()
      cls.D2.add_edges_from(
          [(0, 3), (1, 0), (1, 2), (2, 4), (4, 1), (4, 3), (4, 2)]
      )
      cls.M = nx.MultiGraph()
      nx.add_path(cls.M, range(4))
      cls.M.add_edge(0, 1)
      cls.S = nx.Graph()
      cls.S.add_edges_from([(0, 0), (1, 1)])
      cls.W = nx.Graph()
      cls.W.add_edges_from([(0, 3), (1, 3), (2, 3)], weight=0.5)
      cls.W.add_edge(0, 2, weight=1)
      S1 = nx.star_graph(4)
      S2 = nx.star_graph(4)
      cls.DS = nx.disjoint_union(S1, S2)
      cls.DS.add_edge(4, 5)
  
imports: import networkx
label_desc: Use image node_id 1 for calling the BaseTestDegreeMixing obj's underlying member method code with example usage: obj.setup_class(cls) without return types