anchor.diff:      | _ -> n, Some u
   
   let rec univ_to_string u =
  +Errors.with_ctx "While printing universe" (fun () ->
     // VD: commented out for testing NBE
     // if not (Options.ugly()) then
     //   let e = Resugar.resugar_universe u Range.dummyRange in
  
positive.code:         end
      | U_max us -> U.format1 "(max %s)" (List.map univ_to_string us |> String.concat ", ")
      | U_unknown -> "unknown"
  
  let univs_to_string us = List.map univ_to_string us |> String.concat ", "
  
  
negative.code: open FStar.Ident
  open FStar.Const
  
  module Errors     = FStar.Errors
  module U          = FStar.Util
  module A          = FStar.Parser.AST
  module Resugar    = FStar.Syntax.Resugar
  module ToDocument = FStar.Parser.ToDocument
  module Pp         = FStar.Pprint
  module Unionfind  = FStar.Syntax.Unionfind
  module C          = FStar.Parser.Const
  module SU         = FStar.Syntax.Util
  
  let rec delta_depth_to_string = function
      | Delta_constant_at_level i   -> "Delta_constant_at_level " ^ string_of_int i
  