def METHOD_NAME(self):
    self.assertEqual(self.layout.images, ())
    # Assign compound list
    self.layout.images = [
        go.layout.Image(layer="above"),
        go.layout.Image(layer="below"),
    ]
    # Stored as list of dicts
    self.assertEqual(
        self.layout.to_plotly_json()["images"],
        [{"layer": "above"}, {"layer": "below"}],
    )
    # Presented as compound tuple
    self.assertEqual(
        self.layout.images,
        (go.layout.Image(layer="above"), go.layout.Image(layer="below")),
    )