py绘制正方形

import turtle
n=2
while n >= 0:

    turtle.forward(100)
    turtle.right(90)
    n=n-1
turtle.forward(100)
turtle.penup()
turtle.goto(0,-50)
turtle.pendown()
turtle.goto(100,-50)
turtle.penup()
turtle.goto(50,-50)
turtle.pendown()
turtle.goto(50,-100)
turtle.right(90)
turtle.right(90)
turtle.penup()
turtle.goto(50,0)
turtle.pendown()
turtle.goto(50,-50)
turtle.done
turtle.mainloop()