docs: def add_var_opt(self,opt,value,short=False):
      """
      Add a variable (macro) option for this node. If the option
      specified does not exist in the CondorJob, it is added so the submit
      file will be correct when written.
      @param opt: option name.
      @param value: value of the option for this node in the DAG.
      """
      macro = self.__bad_macro_chars.sub( r'', opt )
      self.__opts['macro' + macro] = value
      self.__job.add_var_opt(opt,short)