internal List <Breadcrumb> RecentBreadcrumbs(long beginTime, long endTime)
        {
            // Recent Breadcrumb's filtered by time . (UserflowReport "systemBreadcrumbs".)
            List <Breadcrumb> answer = new List <Breadcrumb>();

            foreach (Breadcrumb breadcrumb in current_session)
            {
                long breadcrumbTime = TimeUtils.StringToTicks(breadcrumb.GetTimestamp());
                bool afterBeginTime = (beginTime <= breadcrumbTime);
                bool beforeEndTime  = (breadcrumbTime <= endTime);
                if (afterBeginTime && beforeEndTime)
                {
                    answer.Add(breadcrumb);
                }
            }
            return(answer);
        }
        internal static long JsonDateToTicks(JToken json)
        {
            // json that IsJsonDate converted to long ticks .
            long answer = 0;

            switch (json.Type)
            {
            case JTokenType.Date:
                answer = ((DateTime)((JValue)json).Value).ToUniversalTime().Ticks;     // ticks
                break;

            case JTokenType.String:
                answer = TimeUtils.StringToTicks((string)((JValue)json).Value);     // ticks
                break;
            }
            return(answer);
        }