code: def test_empty(self):
      G = nx.Graph()
      assert nx.pagerank(G) == {}
      assert _pagerank_python(G) == {}
      assert _pagerank_numpy(G) == {}
      assert nx.google_matrix(G).shape == (0, 0)
  
imports: import random
  import pytest
  import networkx
  from networkx.classes.tests import dispatch_interface
  from networkx.algorithms.link_analysis.pagerank_alg import _pagerank_numpy, _pagerank_python, _pagerank_scipy
label_desc: Use image node_id 12 for calling the TestPageRank obj's underlying member method code with example usage: obj.test_empty() without return types