'Tests the edge boundary of a multigraph.'

def test_multigraph(self):

    G = nx.MultiGraph((list(nx.cycle_graph(5).edges()) * 2))
    S = {0, 1}
    boundary = list(nx.edge_boundary(G, S))
    expected = [(0, 4), (0, 4), (1, 2), (1, 2)]
    assert_equal(boundary, expected)
