Koch fractals

fractals.py

import turtle
def koch(t, order, size):
    """
       Make turtle t draw a Koch fractal of 'order' and 'size'.
       Leave the turtle facing the same direction.
    """

    if order == 0:          # The base case is just a straight line
        t.forward(size)
    else:
        koch(t, order-1, size/3)   # Go 1/3 of the way
        t.left(60)
        koch(t, order-1, size/3)
        t.right(120)
        koch(t, order-1, size/3)
        t.left(60)
        koch(t, order-1, size/3)

wn = turtle.Screen()        # creates a graphics window
alex = turtle.Turtle()      # create a turtle named alex
koch(alex,4,300)

wn.exitonclick()