anchor.diff:  upsert_cookie(Auth, Req) ->
     trace("upserting cookie"),
     case cowboy_req:cookie(<<"skuapso-session">>, Req) of
  -    {undefined, Req1} -> set_cookie(Auth, Req1);
  +    {Val, Req1} when Val =:= undefined; Val =:= <<>> -> set_cookie(Auth, Req1);
       {Val, Req1} ->
         ska_session:set_cookie(Auth, Val),
         trace("returning from upsert"),
  
positive.code:       authenticated(Auth, Req1, State);
      _ ->
        case cowboy_req:cookie(<<"skuapso-session">>, Req) of
          {Val, Req1} when Val =/= undefined ->
            authenticated({cookie, Val}, Req1, State);
          _ ->
            unauthenticated(Req, State)
  
negative.code: delete_cookie(Auth, Req) ->
    trace("deleting cookie"),
    ska_session:delete_cookie(Auth),
    cowboy_req:set_resp_cookie(<<"skuapso-session">>, <<>>, [{path, "/"}, {max_age, 0}], Req).
  