anchor.diff:      | None -> lg
       | Some x -> S.mk_Tm_app lg [S.as_arg x] None loc
     in
  +  let prob =
      {
       pid=next_pid();
       lhs=lhs;
  
positive.code:           new_problem wl env bound EQ this_flex None tp.loc
                  (if flip then "joining refinements" else "meeting refinements")
        in
        let _ = if Env.debug env <| Options.Other "Rel"
                then let wl' = {wl with attempting=TProb eq_prob::sub_probs} in
                     BU.print1 "After meet/join refinements: %s\n" (wl_to_string wl') in
  
negative.code:      reason=reason::p_reason orig;
       loc=p_loc orig;
       rank=None;
      } in
      def_check_prob reason (TProb p);
      p
  
  let guard_on_element wl problem x phi =
      match problem.element with
          | None ->
  