void Remove0()
            {
                if (_removed)
                {
                    return;
                }

                _removed = true;
                try
                {
                    _handler.HandlerRemoved(this);
                }
                catch (Exception cause)
                {
                    _ = FireExceptionCaught(
                        new ChannelPipelineException($"{StringUtil.SimpleClassName(_handler)}.handlerRemoved() has thrown an exception.", cause));
                }
            }