https://stackoverflow.com/questions/9475241/split-string-every-nth-character
>>> line = ‘1234567890‘
>>> n = 2
>>> [line[i:i+n] for i in range(0, len(line), n)]
[‘12‘, ‘34‘, ‘56‘, ‘78‘, ‘90‘]
Split string every nth character?
原文：http://www.cnblogs.com/antflow/p/7607567.html