plusPeriod method
Adds a Period of time.
This acts on the date parts in exactly the same way as LocalDate.plusPeriod() and leaves the time untouched.
var d = LocalDateTime(2000);
d.plusPeriod(Period(days: 1)) == LocalDateTime(2000, 1, 2);
Implementation
@override
LocalDateTime plusPeriod(Period amount) =>
LocalDateTime.combine(date.plusPeriod(amount), time);