def METHOD_NAME():
    G = Graph([1, 2, 3, 4, 5], [(1, 2), (2, 3)])
    added_mobjects = G.add_edges((1, 3))
    assert str(added_mobjects.submobjects) == "[Line]"
    assert str(G) == "Undirected graph on 5 vertices and 3 edges"
    assert set(G.vertices.keys()) == {1, 2, 3, 4, 5}
    assert set(G.edges.keys()) == {(1, 2), (2, 3), (1, 3)}
    added_mobjects = G.add_edges((1, 42))
    assert str(added_mobjects.submobjects) == "[Dot, Line]"
    assert str(G) == "Undirected graph on 6 vertices and 4 edges"
    assert set(G.vertices.keys()) == {1, 2, 3, 4, 5, 42}
    assert set(G.edges.keys()) == {(1, 2), (2, 3), (1, 3), (1, 42)}
    added_mobjects = G.add_edges((4, 5), (5, 6), (6, 7))
    assert len(added_mobjects) == 5
    assert str(G) == "Undirected graph on 8 vertices and 7 edges"
    assert set(G.vertices.keys()) == {1, 2, 3, 4, 5, 42, 6, 7}
    assert set(G._graph.nodes()) == set(G.vertices.keys())
    assert set(G.edges.keys()) == {
        (1, 2),
        (2, 3),
        (1, 3),
        (1, 42),
        (4, 5),
        (5, 6),
        (6, 7),
    }
    assert set(G._graph.edges()) == set(G.edges.keys())