It encapsulates some date operations like sum. The result will be the
calculated date when calling the nextDateByInterval method, given the
date, periodicity, and skipInterval parameters.
For example, given a date of 2019-12-31, monthly periodicity, and skip
interval 0, the results will be 2020-01-31. Also, if the skip interval
is 1, the result is 2020-02-29. This is because the next date will add
another month to the current range.
