code: def test_is_frozen(self):
      assert not nx.is_frozen(self.G)
      G = nx.freeze(self.G)
      assert G.frozen == nx.is_frozen(self.G)
      assert G.frozen
  
imports: import random
  import pytest
  import networkx
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 19 for calling the TestFunction obj's underlying member method code with example usage: obj.test_is_frozen() without return types