let label env lab wp =
on_context env "label" wp Keep_opened (Label_assigns lab)
(fun env _assigns p ->
if lab = Clabels.Here then p else
match L.find_mem env lab with
| Some at ->
let here = L.mem_at env Clabels.Here in
let wp = WpModel.update ~at ~here p in
Clabels.label F.p_named lab wp
| None -> p)