previousMonth method
Retuns a new DateTime
in the previous calendar month.
If the month is January (01), the retuned DateTime
is in the previous year
Implementation
static DateTime previousMonth(DateTime m) {
var year = m.year;
var month = m.month;
if (month == 1) {
year--;
month = 12;
} else {
month--;
}
return new DateTime(year, month);
}