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; mandatory; phonology will present in the output',required=True)
parser.add_argument('--output',metavar='output-file',help='Output file for the generator. The file is printed to standard output if not given.',default='')