code: def test_second_graph_empty(self):
      G1 = nx.Graph([(0, 1), (1, 2)])
      G2 = nx.Graph()
      assert not vf2pp_is_isomorphic(G1, G2)
  
imports: import itertools
  import pytest
  import networkx
  from networkx import vf2pp_is_isomorphic, vf2pp_isomorphism
label_desc: Use image node_id 2 for calling the TestPreCheck obj's underlying member method code with example usage: obj.test_second_graph_empty() without return types