anchor.diff:                              if pat_discriminates b
                               then
                                 let (_, _, t') = SS.open_branch b in
  -                              match head_matches_delta env wl s t' with
  +                              match head_matches_delta env s t' with
                                 | FullMatch, _
                                 | HeadMatch _, _ ->
                                   true
  
positive.code:     | _ -> MisMatch(delta_depth_of_term env t1, delta_depth_of_term env t2)
  
  (* Does t1 head-match t2, after some delta steps? *)
  let head_matches_delta env wl t1 t2 : (match_result * option<(typ*typ)>) =
      let maybe_inline t =
          let head = U.head_of t in
          if Env.debug env <| Options.Other "RelDelta" then
  
negative.code:         let pairwise t1 t2 wl =
              if Env.debug env <| Options.Other "Rel"
              then BU.print2 "[meet/join]: pairwise: %s and %s\n" (Print.term_to_string t1) (Print.term_to_string t2);
              let mr, ts = head_matches_delta env t1 t2 in
              match mr with
              | HeadMatch true
              | MisMatch _ ->
  