code: def test_isolates():
      G = nx.Graph()
      G.add_edge(0, 1)
      G.add_nodes_from([2, 3])
      assert sorted(nx.isolates(G)) == [2, 3]
  
imports: import networkx
label_desc: Use image node_id 2 for calling a global function with example usage: test_isolates() without return types