code: def force_option_value(self, opt_name, value):
          
          if not self.has_option(opt_name):
              raise ValueError("Unknow option name (%s)" % opt_name)
          self._options[opt_name].default = value # also change the value
          self._options[opt_name].hidden = True
docs: force the (default) value of an option.
          The option is then no more listed by :func:`get_options()`.
          
          :param opt_name: option name
          :type opt_name: str
          :param value: option value