# from http://rosettacode.org/wiki/Yin_and_yang#Python
import math
def yinyang(n=3):
	radii   = [i * n for i in [1, 3, 6]]
	ranges  = [list(range(-r, r+1)) for r in radii]
	squares = [[ (x,y) for x in rnge for y in rnge]
		   for rnge in ranges]
	circles = [[ (x,y) for x,y in sqrpoints
		     if math.hypot(x,y) <= radius ]
		   for sqrpoints, radius in zip(squares, radii)]
	m = {(x,y):' ' for x,y in squares[-1]}
	for x,y in circles[-1]:
		m[x,y] = '*'
	for x,y in circles[-1]:
		if x>0: m[(x,y)] = '.'
	for x,y in circles[-2]:
		m[(x,y+3*n)] = '*'
		m[(x,y-3*n)] = '.'
	for x,y in circles[-3]:
		m[(x,y+3*n)] = '.'
		m[(x,y-3*n)] = '*'
	return '\n'.join(''.join(m[(x,y)] for x in reversed(ranges[-1])) for y in ranges[-1])

def test():
    return yinyang()

Handle Y' rosetta code series
Handle Y' rosetta code series

A very beautiful one, that once again raised a lot of errors...
