new_contents: # -*- coding: utf-8 -*-
  """
  oss2.headers
  ~~~~~~~~
  这个模块包含了发送http请求的header, 类型为dict
  """
  
  OSS_SERVER_SIDE_ENCRYPTION = "x-oss-server-side-encryption"
  OSS_SERVER_SIDE_ENCRYPTION_KEY_ID = "x-oss-server-side-encryption-key-id"
  
  class requestHeader(dict): 
      def __init__(self, *arg, **kw): 
          super(requestHeader, self).__init__(*arg, **kw)
  
      def setServerSideEncryption(self, algorithm=None, cmk_id=None):
          if algorithm is "AES256":
              self[OSS_SERVER_SIDE_ENCRYPTION] = "AES256"
          elif algorithm is "KMS":
              self[OSS_SERVER_SIDE_ENCRYPTION] = "KMS"
              if cmk_id is not None:
                  self[OSS_SERVER_SIDE_ENCRYPTION_KEY_ID] = cmk_id
          else:
              return
  
subject: add requestHeader