def get_repository_nodes(self,<EOL>repository_id=None,<EOL>ancestor_levels=None,<EOL>descendant_levels=None,<EOL>include_siblings=None):
return<EOL>
Gets a portion of the hierarchy for the given repository.

        :param repository_id: the ``Id`` to query
        :type repository_id: ``osid.id.Id``
        :param ancestor_levels: the maximum number of ancestor levels to include. A value of 0
            returns no parents in the node.
        :type ancestor_levels: ``cardinal``
        :param descendant_levels: the maximum number of descendant levels to include. A value
            of 0 returns no children in the node.
        :type descendant_levels: ``cardinal``
        :param include_siblings: ``true`` to include the siblings of the given node, ``false``
            to omit the siblings
        :type include_siblings: ``boolean``
        :return: the specified repository node
        :rtype: ``osid.repository.RepositoryNode``
        :raise: ``NotFound`` -- ``repository_id`` not found
        :raise: ``NullArgument`` -- ``repository_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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