let tree_in_entry prev_symb tree =
                  function
                  | Dlevels levels ->
                      let rec search_levels =
                        (function
                         | [] -> tree
                         | level :: levels ->
                             (match search_level level with
                              | Some tree -> tree
                              | None -> search_levels levels))
                      and search_level level =
                        (match search_tree level.lsuffix with
                         | Some t ->
                             Some
                               (Node
                                  { node = Sself; son = t; brother = DeadEnd;
                                  })
                         | None -> search_tree level.lprefix)
                      and search_tree t =
                        if (tree <> DeadEnd) && (t == tree)
                        then Some t
                        else
                          (match t with
                           | Node n ->
                               (match search_symbol n.node with
                                | Some symb ->
                                    Some
                                      (Node
                                         {
                                           node = symb;
                                           son = n.son;
                                           brother = DeadEnd;
                                         })
                                | None ->
                                    (match search_tree n.son with
                                     | Some t ->
                                         Some
                                           (Node
                                              {
                                                node = n.node;
                                                son = t;
                                                brother = DeadEnd;
                                              })
                                     | None -> search_tree n.brother))
                           | LocAct (_, _) | DeadEnd -> None)
                      and search_symbol symb =
                        (match symb with
                         | Snterm _ | Snterml (_, _) | Slist0 _ |
                             Slist0sep (_, _) | Slist1 _ | Slist1sep (_, _) |
                             Sopt _ | Stry _ | Stoken _ | Stree _ |
                             Skeyword _ when symb == prev_symb -> Some symb
                         | Slist0 symb ->
                             (match search_symbol symb with
                              | Some symb -> Some (Slist0 symb)
                              | None -> None)
                         | Slist0sep (symb, sep) ->
                             (match search_symbol symb with
                              | Some symb -> Some (Slist0sep (symb, sep))
                              | None ->
                                  (match search_symbol sep with
                                   | Some sep -> Some (Slist0sep (symb, sep))
                                   | None -> None))
                         | Slist1 symb ->
                             (match search_symbol symb with
                              | Some symb -> Some (Slist1 symb)
                              | None -> None)
                         | Slist1sep (symb, sep) ->
                             (match search_symbol symb with
                              | Some symb -> Some (Slist1sep (symb, sep))
                              | None ->
                                  (match search_symbol sep with
                                   | Some sep -> Some (Slist1sep (symb, sep))
                                   | None -> None))
                         | Sopt symb ->
                             (match search_symbol symb with
                              | Some symb -> Some (Sopt symb)
                              | None -> None)
                         | Stry symb ->
                             (match search_symbol symb with
                              | Some symb -> Some (Stry symb)
                              | None -> None)
                         | Stree t ->
                             (match search_tree t with
                              | Some t -> Some (Stree t)
                              | None -> None)
                         | _ -> None)
                      in search_levels levels
                  | Dparser _ -> tree