code: def test_to_edgelist_edge_key_col_exists(self):
      G = nx.path_graph(10, create_using=nx.MultiGraph)
      G.add_weighted_edges_from((u, v, u) for u, v in list(G.edges()))
      nx.set_edge_attributes(G, 0, name="edge_key_name")
      pytest.raises(
          nx.NetworkXError,
          nx.to_pandas_edgelist,
          G,
          edge_key="edge_key_name",
      )
  
imports: import pytest
  import networkx
  from networkx.utils import edges_equal, graphs_equal, nodes_equal
label_desc: Use image node_id 14 for calling the TestConvertPandas obj's underlying member method code with example usage: obj.test_to_edgelist_edge_key_col_exists() without return types