class_docstr: Unit tests for the treewidth_min_fill_in function.
docstr: Test empty graph
docstr_tok: ["Test","empty","graph"]
code: def test_empty_graph(self):
      """Test empty graph"""
      G = nx.Graph()
      _, _ = treewidth_min_fill_in(G)
  
imports: import itertools
  import networkx
  from networkx.algorithms.approximation import treewidth_min_degree, treewidth_min_fill_in
  from networkx.algorithms.approximation.treewidth import MinDegreeHeuristic, min_fill_in_heuristic
label_desc: Use image node_id 5 for calling the TestTreewidthMinFillIn obj's underlying member method code with example usage: obj.test_empty_graph() without return types