anchor.diff:        let explore_left = cmp > 0 in
         let explore_right = cmp <= 0 || include_middle in
         let matches = if explore_right then aux rtr prefix acc else acc in
  -      let matches = if include_middle then v :: matches else matches in
  +      let matches = if include_middle then (k, v) :: matches else matches in
         let matches = if explore_left then aux ltr prefix matches else matches in
         matches in
     aux tr prefix []
  
positive.code:   trie_empty
  
  let insert (tbl: table) (c: candidate) =
    let keys = keys_of_candidate c in
    trie_insert tbl keys c
  
  let autocomplete =
  
negative.code: type candidate =
  | Lid of lid
  
  let pth_of_candidate (c: candidate) =
    match c with
    | Lid l -> List.map FStar.Ident.text_of_id (FStar.Ident.ids_of_lid l)
  
  