code: def _lookup_by_mapping():
          
          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 []
docs: 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
          for Arch where the distro's ID changes (Manjaro, Antergos, etc...)
          But the "ID_LIKE" field is always (?) `arch`.