def scatter(x, y, z, color=(1, 0, 0), s=0.01):
    global _last_figure
    fig = _last_figure
    if fig is None:
        fig = volshow(None)
    fig.scatter = Scatter(x=x, y=y, z=z, color=color, size=s)
    fig.volume.scatter = fig.scatter
    return fig