code: def test_connected_isolated_nodes():
      G = nx.complete_graph(4)
      G.add_node(max(G) + 1)
      assert nx.is_connected(G) is False
      assert nxcg.is_connected(G) is False
      assert nx.number_connected_components(G) == 2
      assert nxcg.number_connected_components(G) == 2
      assert sorted(nx.connected_components(G)) == [{0, 1, 2, 3}, {4}]
      assert sorted(nxcg.connected_components(G)) == [{0, 1, 2, 3}, {4}]
      assert nx.node_connected_component(G, 0) == {0, 1, 2, 3}
      assert nxcg.node_connected_component(G, 0) == {0, 1, 2, 3}
      assert nx.node_connected_component(G, 4) == {4}
      assert nxcg.node_connected_component(G, 4) == {4}
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_connected_isolated_nodes() without return types