monthsAgo method
Return the point in time months
ago on the same date.
Implementation
DateTime monthsAgo(int months) {
var time = now();
var m = (time.month - months - 1) % 12 + 1;
var y = time.year - (months + 12 - time.month) ~/ 12;
var d = clampDayOfMonth(year: y, month: m, day: time.day);
return DateTime(
y, m, d, time.hour, time.minute, time.second, time.millisecond);
}