@Override
    DfaValue makeDfaValue(DfaValueFactory factory, DfaCallArguments arguments) {
      if (arguments.myArguments.length <= myIndex) {
        return factory.getUnknown();
      }
      return arguments.myArguments[myIndex];
    }
@Override
    DfaValue makeDfaValue(DfaValueFactory factory, DfaCallArguments arguments)