code: def test_add_remove(self):
      # Test add_node and remove_node acting for various nbunch
      G = self.G()
      G.add_node("m")
      assert G.has_node("m")
      G.add_node("m")  # no complaints
      pytest.raises(nx.NetworkXError, G.remove_node, "j")
      G.remove_node("m")
      assert list(G) == []
  
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 7 for calling the HistoricalTests obj's underlying member method code with example usage: obj.test_add_remove() without return types