import turtle

fenster_breite = 800
fenster_hoehe = 800

screen = turtle.Screen()

screen.setup(fenster_breite, fenster_hoehe)

anna = turtle.Turtle()

b = 100
h = 100

stufe = 2

anna.penup()
anna.goto(-fenster_breite/2,0)
anna.pendown()

for i in range(0, stufe):
    anna.fd(b)
    anna.left(90)
    anna.fd(h)
    anna.right(90)

for i in range(0, stufe):
    anna.fd(b)
    anna.right(90)
    anna.fd(h)
    anna.left(90)

anna.fd(b)

turtle.done()