code: def setup_method(self):
      self.DG = nx.path_graph(9, create_using=nx.DiGraph())
      self.uv = nx.to_undirected(self.DG)
      self.MDG = nx.path_graph(9, create_using=nx.MultiDiGraph())
      self.Muv = nx.to_undirected(self.MDG)
  
imports: import pytest
  import networkx
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 1 for calling the TestToUndirected obj's underlying member method code with example usage: obj.setup_method() without return types