code: def mark_as_duplicate(self, duplicated_cid, master_cid, msg=''):
          
          content_id_from = self.get_post(duplicated_cid)["id"]
          content_id_to = self.get_post(master_cid)["id"]
          params = {
              "cid_dupe": content_id_from,
              "cid_to": content_id_to,
              "msg": msg
          }
          return self._rpc.content_mark_duplicate(params)
docs: Mark the post at ``duplicated_cid`` as a duplicate of ``master_cid``
  
          :type  duplicated_cid: int
          :param duplicated_cid: The numeric id of the duplicated post
          :type  master_cid: int
          :param master_cid: The numeric id of an older post. This will be the
              post that gets kept and ``duplicated_cid`` post will be concatinated
              as a follow up to ``master_cid`` post.
          :type msg: string
          :param msg: the optional message (or reason for marking as duplicate)
          :returns: True if it is successful. False otherwise