public static string Build(string prevAction, string nextAction, Dictionary <string, string> data = null)
        {
            var td = new ViberBotTrackingData();

            td.PrevAction = prevAction;
            td.NextAction = nextAction;
            if (data != null)
            {
                td.Data = data;
            }

            return(JsonConvert.SerializeObject(td));
        }
        public static string Empty()
        {
            var td = new ViberBotTrackingData();

            return(JsonConvert.SerializeObject(td));
        }