code: def test_relabel_multigraph_merge_copy(self):
      G = nx.MultiGraph([(0, 1), (0, 2), (0, 3)])
      G[0][1][0]["value"] = "a"
      G[0][2][0]["value"] = "b"
      G[0][3][0]["value"] = "c"
      mapping = {1: 4, 2: 4, 3: 4}
      H = nx.relabel_nodes(G, mapping, copy=True)
      assert {"value": "a"} in H[0][4].values()
      assert {"value": "b"} in H[0][4].values()
      assert {"value": "c"} in H[0][4].values()
  
imports: import pytest
  import networkx
  from networkx.generators.classic import empty_graph
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 22 for calling the TestRelabel obj's underlying member method code with example usage: obj.test_relabel_multigraph_merge_copy() without return types