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

        :return: Method success.
        :rtype: bool

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

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

        for model in umbra.ui.models.GraphModel.find_model(self):
            model.node_changed(self)
        return True