def get_parent(self):
        if self.parent_id:
            for model in CascadeModelBase._get_cascade_elements():
                try:
                    return model.objects.get(id=self.parent_id)
                except ObjectDoesNotExist:
                    pass
Get a list of the Docker images that are not already installed/pulled.
dataset/ETHPy150Open jrief/djangocms-cascade/cmsplugin_cascade/models_base.py/CascadeModelBase.get_parent--crossover with--dataset/ETHPy150Open tethysplatform/tethys/tethys_apps/cli/docker_commands.py/get_images_to_install