docs: def encrypt_message(self, reply, timestamp=None, nonce=None):
          """
          加密微信回复
          :param reply: 加密前的回复
          :type reply: WeChatReply 或 XML 文本
          :return: 加密后的回复文本
          """
          if hasattr(reply, "render"):
              reply = reply.render()
  
          timestamp = timestamp or to_text(int(time.time()))
          nonce = nonce or generate_token(5)
          encrypt = to_text(self.prp_crypto.encrypt(reply, self.app_id))
          signature = get_signature(self.token, timestamp, nonce, encrypt)
          return to_text(
              self.ENCRYPTED_MESSAGE_XML.format(
                  encrypt=encrypt,
                  signature=signature,
                  timestamp=timestamp,
                  nonce=nonce
              )
          )