code: def test_null(self):
      null = nx.null_graph()
      assert list(null.degree()) == []
      assert dict(null.degree()) == {}
  
imports: import pytest
  import networkx
  from networkx import convert_node_labels_to_integers
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 23 for calling the HistoricalTests obj's underlying member method code with example usage: obj.test_null() without return types