let move = F.parent q' ++ F.previous_sibling q' in
(if self then F.stay q ++ F.stay q' else F.stay q'),
(q', [ QNameSet.any => move ++ F.parent q])
let move = F.parent q' ++ F.previous_sibling q' in
(if self then F.stay q ++ F.stay q' else F.stay q'),
(q', [ QNameSet.any => move ++ F.parent q])