code: def decrypt(self, ciphertext):
          '''
          Decrypt a message, validating its sequence number is as we expect.
  
          Args:
              ciphertext (bytes): The message to decrypt and verify.
  
          Returns:
              mesg: A mesg.
  
          Raises:
              s_exc.CryptoErr: If the message decryption fails or the sequence number was unexpected.
          '''
  
          plaintext = self._rx_tinh.dec(ciphertext)
          if plaintext is None:
              logger.error('Message decryption failure')
              raise s_exc.CryptoErr(mesg='Message decryption failure')
  
          seqn = next(self._rx_sn)
  
          sn, mesg = s_msgpack.un(plaintext)
          if sn != seqn:
              logger.error('Message out of sequence: got %d expected %d', sn, seqn)
              raise s_exc.CryptoErr(mesg='Message out of sequence', expected=seqn, got=sn)
  
          return mesf decrypt(self, ciphertext):
          '''
          Decrypt a message, validating its sequence number is as we expect.
  
          Args:
              ciphertext (bytes): The message to decrypt and verify.
  
          Returns:
              mesg: A mesg.
  
          Raises:
              s_exc.CryptoErr: If the message decryption fails or the sequence number was unexpected.
          '''
  
          plaintext = self._rx_tinh.dec(ciphertext)
          if plaintext is None:
              logger.error('Message decryption failure')
              raise s_exc.CryptoErr(mesg='Message decryption failure')
  
          seqn = next(self._rx_sn)
  
          sn, mesg = s_msgpack.un(plaintext)
          if sn != seqn:
              logger.error('Message out of sequence: got %d expected %d', sn, seqn)
              raise s_exc.CryptoErr(mesg='Message out of sequence', expected=seqn, got=sn)
  
          return mesg
docs: Decrypt a message, validating its sequence number is as we expect.
  
          Args:
              ciphertext (bytes): The message to decrypt and verify.
  
          Returns:
              mesg: A mesg.
  
          Raises:
              s_exc.CryptoErr: If the message decryption fails or the sequence number was unexpected.