code: def test_k_factor3(self):
      g = gen.grid_2d_graph(4, 4)
      with pytest.raises(nx.NetworkXUnfeasible):
          reg.k_factor(g, 3)
  
imports: import pytest
  import networkx
  import networkx
  import networkx.algorithms.regular
  import networkx.generators
label_desc: Use image node_id 4 for calling the TestKFactor obj's underlying member method code with example usage: obj.test_k_factor3() without return types