parser.add_argument('-c','--current',action='store_true',help='install current HEAD')
parser.add_argument('-i','--install',action='store_true',help='install various releases from %s'%ARCHIVE)
parser.add_argument('-i','--install',default=None,nargs='?',const=' ',help='install various releases from %s (default all, otherwise specify them separated with whitespaces, eg. "2018-01 2019.03")'%ARCHIVE)