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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 unpack_bytes(self):
 """Unpack a utf-8 string encoded as described in MQTT Version 3.1.1 section 1.5.3 line 177. This is a 16-bit unsigned length followed by a utf-8 encoded string. Returns ------- int Number of bytes consumed bytes A bytes object extracted from the underlying stream. """

        num_bytes_consumed, b = decode_bytes(self.__f)
        self.__num_bytes_consumed += num_bytes_consumed
        return num_bytes_consumed, b