docs: def qteAddMode(self, mode: str, value):
          """
          Append label for ``mode`` and display ``value`` on it.
  
          |Args|
  
          * ``mode`` (**str**): mode of mode.
          * ``value`` (**object**): value of mode.
  
          |Returns|
  
          * **None**
  
          |Raises|
  
          * **QtmacsArgumentError** if at least one argument has an invalid type.
          """
          # Add the label to the layout and the local mode list.
          label = self._qteGetLabelInstance()
          label.setText(value)
          self._qteModeList.append((mode, value, label))
          self._qteUpdateLabelWidths()