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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 lookup_init_systems(self):
 """Return the relevant init system and its version. This will try to look at the mapping first. If the mapping doesn't exist, it will try to identify it automatically. Windows lookup is not supported and `nssm` is assumed. """

        if utils.IS_WIN:
            logger.debug(
                'Lookup is not supported on Windows. Assuming nssm...')
            return ['nssm']
        if utils.IS_DARWIN:
            logger.debug(
                'Lookup is not supported on OS X, Assuming launchd...')
            return ['launchd']

        logger.debug('Looking up init method...')
        return self._lookup_by_mapping() \
            or self._init_sys_auto_lookup()