Koch Snowflake in python

http://en.wikipedia.org/wiki/Koch_snowflake

by hirbod:

def koch(a,b,c,d,n):
    if n>0:
        ht()
        x=abs(a-c)
        y=abs(b-d)
        l=sqrt(x**2+y**2)
        pencolor("#000000")
        pu()    
        goto(a,b)
        th=towards(c,d)
        pd()
        seth(th)
        fd(l/3.0)
        p=pos()[0]
        q=pos()[1]
        seth(th+60)
        fd(l/3.0)
        u=pos()[0]
        v=pos()[1]
        seth(th-60)
        fd(l/3.0)
        j=pos()[0]
        k=pos()[1]
        pd()
        seth(th)
        pencolor("#FFFFFF")
        bk(l/3.0)
        fd(l/3.0)
        pencolor("#000000")
        fd(l/3.0)
        koch(p,q,u,v,n-1)
        koch(u,v,j,k,n-1)
        koch(a,b,p,q,n-1)
        koch(j,k,c,d,n-1)
    
from math import *
import os
from turtle import *

speed(0)
N=4 # Depth of Fractal
koch(-200,80,200,80,N)
koch(0,80-200*sqrt(3.0),-200,80,N)
koch(200,80,0,80-200*sqrt(3.0),N)
pu()
goto(-80,-50)
write("Koch Snowflake",False,"left",("Tahoma", 18, "italic"))
os.system("pause")