Returns all service statuses

def _get_svc_list(service_status):
    '''
    Returns all service statuses
    '''
    prefix = '/etc/rc.d/'
    ret = set()
    lines = glob.glob('{0}*'.format(prefix))
    for line in lines:
        svc = _get_svc(line, service_status)
        if svc is not None:
            ret.add(svc)

    return sorted(ret)