def path(self, which=None):
        """Extend ``nailgun.entity_mixins.Entity.path``.

        The format of the returned path depends on the value of ``which``:

        incremental_update
            /content_view_versions/incremental_update
        promote
            /content_view_versions/<id>/promote

        ``super`` is called otherwise.

        """
        if which in ('incremental_update', 'promote'):
            prefix = 'base' if which == 'incremental_update' else 'self'
            return '{0}/{1}'.format(
                super(ContentViewVersion, self).path(prefix),
                which
            )
        return super(ContentViewVersion, self).path(which)