GAE、Python处理twitter消息长度限制

def filterTweet(tweet):
  if(tweet.find("转发")!=-1):
    return ""
  if tweet[0:1]=='>':
    tweet=tweet[1:]
  if(len(unicode(tweet,'utf-8'))>140):
    return tweet.decode('utf-8')[0:114].encode('utf-8') + '…' + tweet.decode('utf-8')[len(unicode(tweet,'utf-8'))-25:].encode('utf-8')
  return tweet