def get_class_info(self, class_name=None, class_id=None):
    """ Retrieves class info associated with class_name or class_id """
    if class_id is not None:
        return self.id_to_class_info[class_id]
    elif class_name is not None:
        return self.name_to_class_info[class_name]
    else:
        raise Exception('Either class_id or class_name has to be provided')