public Canvas canvas() {
        Canvas canvas = new Canvas(getLowerBound(), getUpperBound());
        canvas.add(this);
        if (name != null) {
            canvas.setTitle(name);
        }
        return canvas;
    }
@Test
    public void testHeatmap() throws Exception {
        System.out.println("Heatmap");

        var canvas = Heatmap.of(Z, Palette.jet(256)).canvas();
        canvas.window();
    }