code: def test_self_loop(self):
      G = self.G()
      G.add_edge("A", "A")  # test self loops
      assert G.has_edge("A", "A")
      G.remove_edge("A", "A")
      G.add_edge("X", "X")
      assert G.has_node("X")
      G.remove_node("X")
      G.add_edge("A", "Z")  # should add the node silently
      assert G.has_node("Z")
  
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 14 for calling the HistoricalTests obj's underlying member method code with example usage: obj.test_self_loop() without return types