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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_by_mapping():
 """Return a the init system based on a constant mapping of distribution+version to init system.. See constants.py for the mapping. A failover of the version is proposed for when no version is supplied. For instance, Arch Linux's version will most probably be "rolling" at any given time, which means that the init system cannot be idenfied by the version of the distro. On top of trying to identify by the distro's ID, if /etc/os-release contains an "ID_LIKE" field, it will be tried. That, again is true But the "ID_LIKE" field is always (?) `arch`. """

        like = distro.like().lower()
        distribution_id = distro.id().lower()
        version = distro.major_version()
        if 'arch' in (distribution_id, like):
            version = 'any'
        init_sys = constants.DIST_TO_INITSYS.get(
            distribution_id, constants.DIST_TO_INITSYS.get(like))
        if init_sys:
            system = init_sys.get(version)
            return [system] if system else []