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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(self, data):
 """ Takes in a byte string and set's the field value based on field definition. :param structure: The message structure class object :param data: The byte string of the data to unpack :return: The remaining data for subsequent fields """

        size = self._get_calculated_size(self.size, data)
        self.set_value(data[0:size])
        return data[len(self):]