/// <summary>
 /// 打开会话
 /// </summary>
 /// <returns>The open.</returns>
 public Task Open()
 {
     return(AVRealtime.GetConnection("Eohx7L4EMfe4xmairXeT7q1w-gzGzoHsz").ContinueWith(t => {
         if (t.IsFaulted)
         {
             AVRealtime.PrintLog(t.Exception.InnerException.Message);
             var tcs = new TaskCompletionSource <bool>();
             tcs.SetException(t.Exception.InnerException);
             return tcs.Task;
         }
         // TODO 在 SDK 上下文中设置
         connection = t.Result;
         return connection.OpenSession(this);
     }).Unwrap());
 }