Trying to make a line follow a random path

I am trying to make a line follow a random path in python, I have to use simplegui to do it. So far I have done enough to make the line follow a random path but after the for loop, the code restarts. I am not that familiar with simplegui, so I am sure there is a good reason for the code restarting but I have no idea how to fix it. I have provided the code below, thanks in advance!

import simplegui
import random

def draw_handler(canvas):
    x=300 #Should be the center; this is the center of 600x600
    y=300
    for i in range(1000):
        direction=random.randint(1,4) #1=up,2=left,3=down,4=right
        if (direction==1):
            canvas.draw_line([x,y],[x,y-3],3,"Black")
            y=y-3
        if (direction==2):
            canvas.draw_line([x,y],[x-3,y],3,"Black")
            x=x-3
        if (direction==3):
            canvas.draw_line([x,y],[x,y+3],3,"Black")
            y=y+3
        if (direction==4):
            canvas.draw_line([x,y],[x+3,y],3,"Black")
            x=x+3


frame = simplegui.create_frame('Testing', 600, 600)
frame.set_canvas_background("White")
frame.set_draw_handler(draw_handler)
frame.start()