code: def test_disjoint_union_multigraph():
      G = nx.MultiGraph()
      G.add_edge(0, 1, key=0)
      G.add_edge(0, 1, key=1)
      H = nx.MultiGraph()
      H.add_edge(2, 3, key=0)
      H.add_edge(2, 3, key=1)
      GH = nx.disjoint_union(G, H)
      assert set(GH) == set(G) | set(H)
      assert set(GH.edges(keys=True)) == set(G.edges(keys=True)) | set(
          H.edges(keys=True)
      )
  
imports: import os
  import pytest
  import networkx
  from networkx.classes.tests import dispatch_interface
  from networkx.utils import edges_equal
label_desc: Use image node_id 16 for calling a global function with example usage: test_disjoint_union_multigraph() without return types