Hermann Grid Illusion with Python Turtle with Source Code

What do you see? Draw this simple shape. Check out this Wikipedia article to know more about this illusion.

import turtle

screen = turtle.Screen()
screen.setup(500,500)
screen.title('Hermann Grid Illusion - PythonTurtle.Academy')
screen.tracer(0)
turtle.hideturtle()
turtle.speed(0)
turtle.bgcolor('black')

turtle.pensize(4)

turtle.color('light gray')
for x in range(-502,500,25):
    turtle.up()
    turtle.goto(x,-500)
    turtle.down()
    turtle.seth(90)
    turtle.fd(1000)
    
for y in range(-502,500,25):
    turtle.up()
    turtle.goto(-500,y)
    turtle.down()
    turtle.seth(0)
    turtle.fd(1000)

turtle.up()
for x in range(-502,500,25):
    for y in range(-502,500,25):        
        turtle.goto(x,y)
        turtle.dot('white')
screen.update()