code: def test_null_graph(self):
      with pytest.raises(nx.NetworkXError):
          bipartite.biadjacency_matrix(nx.Graph(), [])
  
file_path: networkx/networkx/algorithms/bipartite/tests/test_matrix.py
imports: import pytest
  import networkx
  from networkx.algorithms import bipartite
  from networkx.utils import edges_equal
label_desc: Use image node_id 4 for calling the TestBiadjacencyMatrix obj's underlying member method code with example usage: obj.test_null_graph() without return types