System.Globalization.Calendar.Add C# (CSharp) Method

        internal DateTime Add(DateTime time, double value, int scale) {
            long millis = (long)(value * scale + (value >= 0? 0.5: -0.5));
            if (millis <= -MaxMillis || millis >= MaxMillis) {
                throw new ArgumentOutOfRangeException("value", Environment.GetResourceString("ArgumentOutOfRange_AddValue"));
            }
            long ticks = time.Ticks + millis * TicksPerMillisecond;
            CheckAddResult(ticks, MinSupportedDateTime, MaxSupportedDateTime);
            return (new DateTime(ticks));
        }