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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 absolutize(self, region_id, relative_address):
 """ Convert a relative address in some memory region to an absolute address. :param region_id: The memory region ID :param relative_address: The relative memory offset in that memory region :return: An absolute address if converted, or an exception is raised when region id does not exist. """


        if region_id == 'global':
            # The global region always bases 0
            return relative_address

        if region_id not in self._region_id_to_address:
            raise SimRegionMapError('Non-existent region ID "%s"' % region_id)

        base_address = self._region_id_to_address[region_id].base_address
        return base_address + relative_address