Triggers the host model(s) :meth:`umbra.ui.models.GraphModel.attribute_changed` method.

        :return: Method success.
        :rtype: bool

def attribute_changed(self):
        """
        Triggers the host model(s) :meth:`umbra.ui.models.GraphModel.attribute_changed` method.

        :return: Method success.
        :rtype: bool
        """

        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