Can't clear the canvas

[lvidarte]

Hi! nice work!

I'm trying calysto turtle with ipywidgets, and I would like to clear the canvas.

How can I do that?

Here is my code

import ipywidgets as widgets
from IPython.display import display, clear_output
from calysto.graphics import *

sides  = widgets.IntSlider(min=3, max=10, description="Sides")
button = widgets.Button(description="Draw!")
canvas = Canvas(size=(400, 400))
turtle = Turtle(canvas, (200, 20), 0)

def draw_polygon(button):

    global sizes, canvas, turtle

    for _ in range(sides.value):
        turtle.forward(50)
        turtle.right(360/sides.value)

    clear_output(wait=True)
    display(sides, button, canvas)

button.on_click(draw_polygon)
display(sides, button, canvas)

If I use canvas.clear() then I get

ValueError: <Polygon [(-10, 5), (0, 0), (-10, -5), (-5, 0)]> is not in list

Thanks!