("-T", Arg.Int set_trace, help_T);
("-V", Arg.Unit print_version, help_V);
("-X", Arg.Unit clear_options, help_X);
("-a", Arg.String ((:=) G.alpha), help_a);
("-b", Arg.Int ((:=) G.first), help_b);
("-T", Arg.Int set_trace, help_T);
("-V", Arg.Unit print_version, help_V);
("-X", Arg.Unit clear_options, help_X);
("-a", Arg.String ((:=) G.alpha), help_a);
("-b", Arg.Int ((:=) G.first), help_b);