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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def decrypt(self, data):
 """ 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 """

        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