Return a list of tuples of available init systems on the
        current machine.

        Note that in some situations (Ubuntu 14.04 for instance) more than
        one init system can be found.

def _init_sys_auto_lookup(self):
        """Return a list of tuples of available init systems on the
        current machine.

        Note that in some situations (Ubuntu 14.04 for instance) more than
        one init system can be found.
        """
        # TODO: Instead, check for executables for systemd and upstart
        # systemctl for systemd and initctl for upstart.
        # An alternative might be to check the second answer here:
        # http://unix.stackexchange.com/questions/196166/how-to-find-out-if-a-system-uses-sysv-upstart-or-systemd-initsystem
        # TODO: Move to each system's implementation
        init_systems = []
        if self._is_init_system_installed('/usr/lib/systemd'):
            init_systems.append('systemd')
        if self._is_init_system_installed('/usr/share/upstart'):
            init_systems.append('upstart')
        if self._is_init_system_installed('/etc/init.d'):
            init_systems.append('sysv')
        return init_systems