import turtle

def koch_curve(length, depth):
    if depth == 0:
        turtle.forward(length)
    else:
        for angle in [60, -120, 60, 0]:
            koch_curve(length / 3, depth - 1)
            turtle.left(angle)

length = 400
depth = 4

turtle.penup()
turtle.goto(-length / 2, 0)
turtle.pendown()
turtle.speed("fastest")
turtle.hideturtle()
for i in range(3):
    koch_curve(length, depth)
    turtle.right(120)

turtle.done()