let enlarge_to_right ~extend_right same_values ei new_vv acc =
if extend_right then
(* look for an interval starting just after i *)
let s_ei = Int.succ ei in
match concerned_intervals Int_Interv.fuzzy_order (s_ei,s_ei) acc
with [] -> acc,ei
| [(ba,ea) as a,vva] ->
assert (Int.equal ba s_ei);
if same_values vva new_vv then
(remove a acc),ea
else acc,ei
| _ -> assert false
else acc,ei