anchor.diff:  %% reached maximum retry limit.
   %% Unknown corr-id:s are ignored.
   %% @end
  --spec nack(buf(), corr_id(), any()) -> {ok, buf()} | {error, ignored}.
  +-spec nack(buf(), brod: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) ->
  
positive.code:     ok
    end.
  
  -spec data_size(key() | value()) -> non_neg_integer().
  data_size(Data) -> brod_utils:bytes(Data).
  
  %%%_* Tests ====================================================================
  
negative.code:         , onwire_count   = 0            :: non_neg_integer()
          , pending        = ?EMPTY_QUEUE :: queue:queue(#req{})
          , buffer         = ?EMPTY_QUEUE :: queue:queue(#req{})
          , onwire         = []           :: [{brod:corr_id(), [#req{}]}]
          }).
  
  -opaque buf() :: #buf{}.
  