public IEnumerable <ChartItem> GetChart([NotNull] IThreatModel model)
        {
            IEnumerable <ChartItem> result = null;

            var severities = model.Severities?
                             .Where(x => x.Visible && x.Id > 0)
                             .OrderByDescending(x => x.Id).ToArray()
                             .ToArray();

            if (severities?.Any() ?? false)
            {
                var list = new List <ChartItem>();

                foreach (var severity in severities)
                {
                    list.Add(new ChartItem(severity.Name, model.CountThreatEvents(severity), severity.BackColor));
                }

                result = list;
            }

            return(result);
        }