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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 activate_conf_set(self, set_name):
        '''Activate a configuration set by name.

        @raises NoSuchConfSetError

        '''
        with self._mutex:
            if not set_name in self.conf_sets:
                raise exceptions.NoSuchConfSetError(set_name)
            self._conf.activate_configuration_set(set_name)