new_contents: import hashlib
  
  def sign(secret, params):
      '''
          params目前只支持字典类型
      '''
  
      keys = parameters.keys()
      keys.sort()
  
      p_string = "%s%s%s" % (secret, \
              ''.join('%s%s' % (key, params[key]) for key in keys), \
              secret)
  
      sign = hashlib.md5(p_string).hexdigest().upper()
  
      return sign
  
subject: add sign function