@abc.abstractmethod<EOL><INDENT>def get_repositories_by_parent_genus_type(self, repository_genus_type):<DEDENT>
return<EOL>
Gets a ``RepositoryList`` corresponding to the given repository genus ``Type`` and include any additional repositories with genus types derived from the specified ``Type``.

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

        :param repository_genus_type: a repository genus type
        :type repository_genus_type: ``osid.type.Type``
        :return: the returned ``Repository list``
        :rtype: ``osid.repository.RepositoryList``
        :raise: ``NullArgument`` -- ``repository_genus_type`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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