def _GetSerializedAttributeContainerList(self, container_type):
    """Retrieves a serialized attribute container list.

    Args:
      container_type (str): attribute container type.

    Returns:
      SerializedAttributeContainerList: serialized attribute container list.
    """
    container_list = self._serialized_attribute_containers.get(
        container_type, None)
    if not container_list:
      container_list = SerializedAttributeContainerList()
      self._serialized_attribute_containers[container_type] = container_list

    return container_list
Retrieves a serialized attribute container list.

    Args:
      container_type (str): attribute container type.

    Returns:
      SerializedAttributeContainerList: serialized attribute container list.