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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 read(self, count):
 """ read count bytes from the underlying buffer and return them as a str. Raises an UnpackException if there is not enough data in the underlying buffer. """


        offset = self.offset
        if self.data:
            avail = len(self.data) - offset
        else:
            avail = 0

        if avail < count:
            raise UnpackException(None, count, avail)

        self.offset = offset + count
        return self.data[offset:self.offset]