ObjectHelper.cs

public static class ObjectHelper {
        public static T? Min<T>(T? x, T? y) where T : struct, IComparable {
            if (x.HasValue && y.HasValue) {
                return x.Value.CompareTo(y.Value) <= 0 ? x : y;
            } else if (x.HasValue) {
                return x;
            } else {
                return y;
            }
        }

        public static T? MinWith<T>(this T? x, T? y) where T : struct, IComparable {
            return Min(x, y);
        }

        public static T? Max<T>(T? x, T? y) where T : struct, IComparable {
            if (x.HasValue && y.HasValue) {
                return x.Value.CompareTo(y.Value) >= 0 ? x : y;
            } else if (x.HasValue) {
                return x;
            } else {
                return y;
            }
        }

        public static T? MaxWith<T>(this T? x, T? y) where T : struct, IComparable {
            return Max(x, y);
        }
    }