code: def test_k_factor1(self):
      g = gen.grid_2d_graph(4, 4)
      g_kf = reg.k_factor(g, 2)
      for edge in g_kf.edges():
          assert g.has_edge(edge[0], edge[1])
      for _, degree in g_kf.degree():
          assert degree == 2
  
imports: import pytest
  import networkx
  import networkx
  import networkx.algorithms.regular
  import networkx.generators
label_desc: Use image node_id 2 for calling the TestKFactor obj's underlying member method code with example usage: obj.test_k_factor1() without return types