These are iso-year-week-day methods for the arithmetic generics.
You cannot add weeks or days to an iso-year-week-day calendar. Adding
days is much more efficiently done by converting to a time point first
as_sys_time(). Adding weeks is equally
as efficient as adding 7 days. Additionally, adding weeks to an invalid
iso-year-week object containing
iso_year_week_day(2019, 53) would be
undefined, as the 53rd ISO week of 2019 doesn't exist to begin with.
# S3 method for clock_iso_year_week_day add_years(x, n, ...)
A iso-year-week-day vector.
An integer vector to be converted to a duration, or a duration
corresponding to the arithmetic function being used. This corresponds
to the number of duration units to add.
These dots are for future extensions and must be empty.
x after performing the arithmetic.
n are recycled against each other.
#> <iso_year_week_day<day>> #>  "2020-W01-1" "2021-W01-1"