code: def test_relabel_nodes_digraph(self):
      G = nx.DiGraph([("A", "B"), ("A", "C"), ("B", "C"), ("C", "D")])
      mapping = {"A": "aardvark", "B": "bear", "C": "cat", "D": "dog"}
      H = nx.relabel_nodes(G, mapping, copy=False)
      assert nodes_equal(H.nodes(), ["aardvark", "bear", "cat", "dog"])
  
imports: import pytest
  import networkx
  from networkx.generators.classic import empty_graph
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 10 for calling the TestRelabel obj's underlying member method code with example usage: obj.test_relabel_nodes_digraph() without return types