ArtistAnimation currently constructs a list of Figures to animate like this:

    if artist.axes.figure not in figs:
        figs.add(artist.axes.figure)

However, some artists (e.g. suptitle) have None as axes, so this code fails. On the other hand, each artist has a get_figure method. Why not change the above code to:

    if artist.get_figure() not in figs:
        figs.add(artist.get_figure())