@abc.abstractmethod<EOL><INDENT>def add_package_version(self, package_id, next_package_id):<DEDENT>
pass<EOL>
Sets the given package to be the next version of another package.

        :param package_id: the ``Id`` of a ``Package``
        :type package_id: ``osid.id.Id``
        :param next_package_id: the ``Id`` of the net package version
        :type next_package_id: ``osid.id.Id``
        :raise: ``AlreadyExists`` -- ``next_package_id`` or ``package_id`` already part of a version chain
        :raise: ``NotFound`` -- ``package_id`` or ``next_package_id`` not found
        :raise: ``NullArgument`` -- ``package_id`` or ``next_package_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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