(** Transform the e into eu or E *)
let process
  : 'a Sig.modifier
  = fun init ->
    let ((v2, c) , ending) = init in

    match ending with
    | None when v2 = Sounds.schwa ->
      (* If there is no more consononant in the syllabe, change the e
         into eu, like in sera *)
      ((Sounds.eu `Closed, c) , ending)
    | Some _ when v2 = Sounds.schwa ->
      (* If there is an ending consonant, change the e into E like essai *)
      ((Sounds.e `Opened, c) , ending)
    | _ -> init