public void ConcurrentLast(IEnumerator work)
            {
                if (work == null)
                {
                    return;
                }
                var realwork = GetRealWorkFromSubWork(work);

                if (_Inner == null)
                {
                    _Inner = realwork;
                }
                else
                {
                    var queue = _Inner as CoroutineWorkQueue;
                    if (queue == null)
                    {
                        var queuec = MakeInnerConcurrent();
                        queuec.AddWork(realwork);
                    }
                    else
                    {
                        var last = queue.LastWork;
                        if (last == null)
                        {
                            queue.AddWork(realwork);
                        }
                        else
                        {
                            var queuec = last as CoroutineMonitorConcurrent;
                            if (queuec != null)
                            {
                                queuec.AddWork(realwork);
                            }
                            else
                            {
                                queuec = new CoroutineMonitorConcurrent();
                                queuec.AddWork(last);
                                queuec.AddWork(realwork);
                            }
                        }
                    }
                }
            }
            protected CoroutineMonitorConcurrent MakeInnerConcurrent()
            {
                var con = _Inner as CoroutineMonitorConcurrent;

                if (con == null)
                {
                    con = new CoroutineMonitorConcurrent();
                    con.AddWork(_Inner);
                    _Inner = con;
                }
                return(con);
            }