anchor.diff:          , onwire_count   = 0            :: non_neg_integer()
           , pending        = ?EMPTY_QUEUE :: queue:queue(#req{})
           , buffer         = ?EMPTY_QUEUE :: queue:queue(#req{})
  -        , onwire         = []           :: [{corr_id(), [#req{}]}]
  +        , onwire         = []           :: [{brod:corr_id(), [#req{}]}]
           }).
   
   -opaque buf() :: #buf{}.
  
positive.code: %% reached maximum retry limit.
  %% Unknown corr-id:s are ignored.
  %% @end
  -spec nack(buf(), corr_id(), any()) -> {ok, buf()} | {error, ignored}.
  nack(#buf{onwire = [{CorrId, _Reqs} | _]} = Buf, CorrId, Reason) ->
    nack_all(Buf, Reason);
  nack(#buf{onwire = OnWire}, CorrIdReceived, _Reason) ->
  
negative.code: %% one comparing to ID1.
  %% Assuming that no clients would send up to 2^26 messages asynchronously.
  %% @end
  -spec is_later_corr_id(brod:corr_id(), brod:corr_id()) -> boolean().
  is_later_corr_id(Id1, Id2) ->
    Diff = abs(Id1 - Id2),
    case Diff < (?MAX_CORR_ID div 2) of
  