private void Plot(Chart chart, Snapshot snapshot, string area)
        {
            var xvals = snapshot.Select(x => x.Timestamp).ToArray();

            var yvals = new double?[0];

            if (xvals.Length != 0)
            {
                for (int i = 0; i < snapshot[0].Labels.Count; i++)
                {
                    yvals = snapshot.Select(y => y.Data[i].HasValue ? new double?(y.Data[i].Value*_scale) : null).ToArray();

                    AddSeriesToChart(chart, xvals, yvals, _min, _max, snapshot[0].Labels[i], area);
                }
            }
        }