from tkinter import *
from random import randint, seed
def demo():
    window = Tk()
    c = Canvas(window, width=320, height=320)
    c.pack()
    colors = ["red", "green", "blue"]
    seed(15110)
    for row in range(0,8):
        for col in range(0,8):
            randcolor = colors[randint(0,2)]
            c.create_rectangle(40*col,40*row,40*(col+1),40*(row+1),fill=randcolor)
    window.mainloop() #keep the window open until we close it
    return None