data Symmetrise : Rel a -> Rel aFwd : r x y -> Symmetrise r x yBwd : r x y -> Symmetrise r y xsym : Symmetrise r ~> flip (Symmetrise r)gmap : (f : (a -> b)) -> p ~> (q `on` f) -> Symmetrise p ~> (Symmetrise q `on` f)map : p ~> q -> Symmetrise p ~> Symmetrise qjoin : Symmetrise (Symmetrise p) ~> Symmetrise p