@classmethod
def register_term_class(cls, term_name, class_or_name):
    """
        Register a Term subclass for a qualified term name.

        :param term_name: Fully-qualified term name. Will be converted to lowercase.
        :param clz: A class, or fully-qualified, dotted class name.
        :return:
        """
    cls.term_classes[term_name.lower()] = class_or_name
