code: def set_output(self,filename,pass_to_command_line=True):
      
      self.__output = filename
      if pass_to_command_line:
        self.add_var_opt('output', filename)
      self.add_output_file(filename)
docs: Add an output to the node by adding a --output option.
      @param filename: option argument to pass as output.
      @bool pass_to_command_line: add output as a variable option.