getMonthDifference method
Gets difference of months between date
and calling object.
Implementation
int getMonthDifference(DateTime date) {
if (year == date.year) return ((date.month - month).abs() + 1);
var months = ((date.year - year).abs() - 1) * 12;
if (date.year >= year) {
months += date.month + (13 - month);
} else {
months += month + (13 - date.month);
}
return months;
}