code: def test_graph_attributes():
      G = nx.DiGraph()
      G.add_nodes_from([1, 2, 3], color="red")
      G.add_edge(1, 2, foo=7)
      G.add_edge(1, 3, foo=10)
      G.add_edge(3, 4, foo=10)
      H = tree_graph(tree_data(G, 1))
      assert H.nodes[1]["color"] == "red"
  
      d = json.dumps(tree_data(G, 1))
      H = tree_graph(json.loads(d))
      assert H.nodes[1]["color"] == "red"
  
imports: import json
  import pytest
  import networkx
  from networkx.readwrite.json_graph import tree_data, tree_graph
label_desc: Use image node_id 2 for calling a global function with example usage: test_graph_attributes() without return types