docstr: Tests that the minimum spanning edges of a multigraph
  preserves edge keys.
docstr_tok: ["Tests","that","the","minimum","spanning","edges","of","a","multigraph","preserves","edge","keys","."]
code: def test_multigraph_keys_min(self):
      """Tests that the minimum spanning edges of a multigraph
      preserves edge keys.
      """
      G = nx.MultiGraph()
      G.add_edge(0, 1, key="a", weight=2)
      G.add_edge(0, 1, key="b", weight=1)
      min_edges = nx.minimum_spanning_edges
      mst_edges = min_edges(G, algorithm=self.algo, data=False)
      assert edges_equal([(0, 1, "b")], list(mst_edges))
  
imports: import pytest
  import networkx
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 1 for calling the MultigraphMSTTestBase obj's underlying member method code with example usage: obj.test_multigraph_keys_min() without return types