python 判斷控制符 unicode str

import codecs
f = codecs.open('unicode.rst', encoding='utf-8')

def rm_control_characters(string):
    return "".join(ch if not unicodedata.category(ch)=='Cc' else ',' ch in unicode(string))

>>> print u'Hello, 你好, bye.'.encode('unicode-escape')
Hello, \u4f60\u597d, bye.