code: def get_parameter(self):
          
          current_index = self.input.currentIndex()
          selected_value = self.input.itemData(current_index, Qt.UserRole)
          if hasattr(selected_value, 'toPyObject'):
              selected_value = selected_value.toPyObject()
  
          try:
              self._parameter.value = selected_value
          except ValueError:
              err = self.raise_invalid_type_exception()
              raise err
  
          radio_button_checked_id = self.default_input_button_group.checkedId()
          # No radio button checked, then default value = None
          if radio_button_checked_id == -1:
              self._parameter.default = None
          # The last radio button (custom) is checked, get the value from the
          # line edit
          elif (radio_button_checked_id
                == len(self._parameter.default_values) - 1):
              self._parameter.default_values[radio_button_checked_id] \
                  = self.custom_value.value()
              self._parameter.default = self.custom_value.value()
          else:
              self._parameter.default = self._parameter.default_values[
                  radio_button_checked_id]
  
          return self._parameter
docs: Obtain list parameter object from the current widget state.
  
          :returns: A DefaultSelectParameter from the current state of widget.