>>> import turtle
>>> import os
>>>
>>> wn = turtle.Screen()
>>> wn.bgcolor("black")
>>> wn.title("Space Invaders")
>>>
>>> delay = raw_input("Press enter to finish")
Press enter to finish
>>> border_pen = turtle.Turtle()
>>> border_pen.hideturtle()
>>> border_pen.speed(0)
>>> border_pen.color("white")
>>> border_pen.penup()
>>> border_pen.setposition(-100,-100)
>>> border_pen.pendown()
>>> border_pen.pensize(3)
>>> for side in range(4):
	border_pen.fd(350)
	border_pen.lt(90)