# -*- coding: utf-8 -*-
from turtle import *

def carre(c):
    down()
    setheading(0)
    for i in range (4) :
        forward(c)
        right(90)
    up()
    return


tracer(4,1000)
hideturtle()
width(1)
for k in range(50):
    for i in range(k):
        if i==0:
            color("black","grey")
            begin_fill()
            carre(10)
            end_fill()
        else:
            color("black")
            carre(10)
        setheading(k*90)
        forward(10)
    
exitonclick()