anchor.diff:  let resugar_arg_qual (q:option<S.arg_qualifier>) : option<A.arg_qualifier> =
     match q with
       | None -> None
  -    | Some (Implicit b) -> Some A.Implicit  //TODO: how should we map this flag back to the surface?
  -    | Some Equality -> Some A.Equality
  +    | Some (S.Implicit b) -> Some A.Implicit  //TODO: how should we map this flag back to the surface?
  +    | Some S.Equality -> Some A.Equality
   
   let rec universe_to_int n u =
     match u with 
  
positive.code:   match (SS.compress x.sort).n with
    //| Tm_type U_unknown
    | Tm_unknown ->
      if (x.ppname.idText.Equals I.reserved_prefix ) then
        mk (A.PatWild)
      else
        mk (A.PatVar(bv_as_unique_ident x, resugar_arg_qual qual))
  
negative.code:       else if BU.starts_with s U.field_projector_prefix then
          let rest = BU.substring_from s (String.length U.field_projector_prefix) in
          let r = BU.split rest U.field_projector_sep in
          begin match r with 
            | [fst; snd] -> 
              let l = lid_of_path [fst] t.pos in
              let r = I.mk_ident (snd, t.pos) in
              mk (A.Projector(l, r ))
            | _ ->
              failwith "not implemented yet"
          end
         else if (lid_equals a C.assert_lid 
              || lid_equals a C.assume_lid
              || Char.uppercase (String.get s 0) <> String.get s 0) then
  