code: def attribute_changed(self):
          
  
          for model in umbra.ui.models.GraphModel.find_model(self):
              headers = model.horizontal_headers.values()
              if not self.name in headers:
                  continue
  
              model.attribute_changed(model.find_node(self), headers.index(self.name))
          return True
docs: Triggers the host model(s) :meth:`umbra.ui.models.GraphModel.attribute_changed` method.
  
          :return: Method success.
          :rtype: bool