code: def decrypt(self, data):
          
          decrypted_data = b""
          for i in range(0, len(data), 8):
              block = data[i:i + 8]
              block_length = len(block)
              if block_length != 8:
                  raise ValueError("DES decryption must be a multiple of 8 "
                                   "bytes")
  
              decrypted_data += self._decode_block(block)
  
          return decrypted_data
docs: DES decrypts the data based on the key it was initialised with.
  
          :param data: The encrypted bytes string to decrypt
          :return: The decrypted bytes string