Export Multiple Canvas/Jpg

Hi I just discovered coreimage and love it. My question is if and if yes how I can export multiple images. E.g. my script generates random versions of a rectangle and every version will be exported to a jpg or a multipage pdf. How can I achieve this? With multiple canvases?

Thanks for your time!

size(200, 200)
background(None)
 
for items in range(10):
    canvas.clear() 
 
    fill(0)
    rect(items*4, items*4, 40, 40)
    canvas.save(str(items) + ".png")

sorry, should be ".jpg"

muchas gracias!!