render mandelbrot set on terminal

mandelbrot.py

import sys
import math

def dot(bits):
    bits = bits & 7 | (bits & 112) >> 1 | (bits & 8) << 3 | bits & 128
    return unichr(0x2800 + bits)

def mandelbrot(x, y, r, iteration=1000):
    xx = 1.4 * float(x - 1.4 * r) / r
    yy = 1.4 * float(y - r) / r
    c = complex(xx, yy)
    r = c
    for i in range(iteration):
        r = r * r + c
        if abs(r) > 2:
            return False

    return True

if len(sys.argv) > 1:
    R = int(sys.argv[1])
else:
    R = 90

for y in range(R/2):
    for x in range(R):
        r = reduce(lambda r, i: r | mandelbrot(x * 2 + ((i & 4) >> 2), y * 4 + (i & 3), R) << i, range(8), 0)
        sys.stdout.write(dot(r).encode('utf8'))
    print