code: def test_multigraph(self):
      G = nx.MultiGraph()
      G.add_edge(1, 2, key="first")
      G.add_edge(1, 2, key="second", color="blue")
      H = node_link_graph(node_link_data(G))
      assert nx.is_isomorphic(G, H)
      assert H[1][2]["second"]["color"] == "blue"
  
file_path: networkx/networkx/readwrite/json_graph/tests/test_node_link.py
imports: import json
  import pytest
  import networkx
  from networkx.readwrite.json_graph import node_link_data, node_link_graph
label_desc: Use image node_id 6 for calling the TestNodeLink obj's underlying member method code with example usage: obj.test_multigraph() without return types