code: def add_var_arg(self,arg_index):
      
      try:
        self.__var_args[arg_index]
      except IndexError:
        if arg_index != self.__arg_index:
          raise CondorDAGJobError, "mismatch between job and node var_arg index"
        self.__var_args.append('$(macroargument%s)' % str(arg_index))
        self.add_arg(self.__var_args[self.__arg_index])
        self.__arg_index += 1
docs: Add a command to the submit file to allow variable (macro) arguments
      to be passed to the executable.