anchor.diff:          , del/2
           , get_api_key/2
           , get_caller/2
  +        , get_corr_id/1
           ]).
   
   -export_type([requests/0]).
  
positive.code: -ifdef(TEST).
  
  next_corr_id_test() ->
    ?assertEqual(0, next_corr_id((1 bsl 31) - 1)).
  
  -endif. % TEST
  
  
negative.code:   {Caller, _ApiKey} = gb_trees:get(CorrId, Sent),
    Caller.
  
  
  %% @doc Get the correction to be sent for the next request.
  -spec get_corr_id(requests()) -> corr_id().
  get_corr_id(#requests{ corr_id = CorrId }) ->
    CorrId.
  
  %%%_* Internal functions =======================================================
  
  next_corr_id(?MAX_CORR_ID) -> 0;
  