code: def get_parameter(self):
          
          radio_button_checked_id = self.input_button_group.checkedId()
          # No radio button checked, then default value = None
          if radio_button_checked_id == -1:
              self._parameter.value = None
          # The last radio button (custom) is checked, get the value from the
          # line edit
          elif radio_button_checked_id == len(self._parameter.options) - 1:
              self._parameter.options[radio_button_checked_id] = \
                  self.custom_value.value()
              self._parameter.value = self.custom_value.value()
          else:
              self._parameter.value = self._parameter.options[
                  radio_button_checked_id]
  
          return self._parameter
docs: Obtain list parameter object from the current widget state.
  
          :returns: A DefaultValueParameter from the current state of widget
          :rtype: DefaultValueParameter