parser.add_argument('--phonology',metavar='phonology',help='id of the phonology on which is based the generator',required=True)
parser.add_argument('--phonologyfile',metavar='phonologyfile',help='file containing the phonology; optional, if provided, examples will be checked for unknown phonemes and phonology will present in the output',default='')
parser.add_argument('--order',metavar='order',help='order of the chain; 1 by default',default=1,type=int)
parser.add_argument('--output',metavar='output-file',help='Output file for the generator. The file is printed to standard output if not given.',default='')