@abc.abstractmethod<EOL><INDENT>def get_items_by_parent_genus_type(self, item_genus_type):<DEDENT>
return<EOL>
Gets an ``ItemList`` corresponding to the given assessment item genus ``Type`` and include any additional assessment items with genus types derived from the specified ``Type``.

        In plenary mode, the returned list contains all known assessment
        items or an error results. Otherwise, the returned list may
        contain only those assessment items that are accessible through
        this session.

        :param item_genus_type: an assessment item genus type
        :type item_genus_type: ``osid.type.Type``
        :return: the returned ``Item`` list
        :rtype: ``osid.assessment.ItemList``
        :raise: ``NullArgument`` -- ``item_genus_type`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure occurred

        *compliance: mandatory -- This method must be implemented.*