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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 get_byte_length(self, decoded=True) -> int: """ Return the length of this message in byte. """

        end = len(self.decoded_bits) if decoded else len(self.__plain_bits)
        end = self.convert_index(end, 0, 2, decoded=decoded)[0]
        return int(end)