code: def setup_class(cls):
      cls.Gi = nx.grid_2d_graph(5, 5)
      cls.Gs = nx.Graph()
      nx.add_path(cls.Gs, "abcdef")
      cls.bigG = nx.grid_2d_graph(25, 25)
  
imports: import pytest
  import networkx
label_desc: Use image node_id 1 for calling the TestLayout obj's underlying member method code with example usage: obj.setup_class(cls) without return types