code: def update(self, volume, display_name=None, display_description=None):
          
          return volume.update(display_name=display_name,
                  display_description=display_description)
docs: Update the specified values on the specified volume. You may specify
          one or more values to update. If no values are specified as non-None,
          the call is a no-op; no exception will be raised.