import random

printdead, printlive = '_#'
maxgenerations = 10
cellcount = 20
offendvalue = '0'

universe = ''.join(random.choice('01') for i in range(cellcount))

neighbours2newstate = {
 '000': '0',
 '001': '0',
 '010': '0',
 '011': '1',
 '100': '0',
 '101': '1',
 '110': '1',
 '111': '0',
 }

for i in range(maxgenerations):
    print "Generation %3i:  %s" % ( i,
          universe.replace('0', printdead).replace('1', printlive) )
    universe = offendvalue + universe + offendvalue
    universe = ''.join(neighbours2newstate[universe[i:i+3]] for i in range(cellcount))