code: function UnassignedAssignment(requisition, arg) {
    var isIncompleteName = (arg.text.charAt(0) === '-');
    this.param = new Parameter(requisition.system.types, {
      name: '__unassigned',
      description: l10n.lookup('cliOptions'),
      type: {
        name: 'param',
        requisition: requisition,
        isIncompleteName: isIncompleteName
      }
    });
  
    // It would be nice to do 'conversion = parm.type.parse(arg, ...)' except
    // that type.parse returns a promise (even though it's synchronous in this
    // case)
    if (isIncompleteName) {
      var lookup = commandModule.getDisplayedParamLookup(requisition);
      var predictions = selectionModule.findPredictions(arg, lookup);
      this.conversion = selectionModule.convertPredictions(arg, predictions);
    }
    else {
      var message = l10n.lookup('cliUnusedArg');
      this.conversion = new Conversion(undefined, arg, Status.ERROR, message);
    }
  
    this.conversion.assignment = this;
  }
docs: Special assignment used when ignoring parameters that don't have a home