These are year-quarter-day methods for the arithmetic generics.

Notably, *you cannot add days to a year-quarter-day*. For day-based
arithmetic, first convert to a time point with `as_naive_time()`

or
`as_sys_time()`

.

## Usage

```
# S3 method for clock_year_quarter_day
add_years(x, n, ...)
# S3 method for clock_year_quarter_day
add_quarters(x, n, ...)
```

## Arguments

- x
`[clock_year_quarter_day]`

A year-quarter-day vector.

- n
`[integer / clock_duration]`

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.

`n`

may be negative to subtract units of duration.- ...
These dots are for future extensions and must be empty.

## Examples

```
x <- year_quarter_day(2019, 1:3)
x
#> <year_quarter_day<January><quarter>[3]>
#> [1] "2019-Q1" "2019-Q2" "2019-Q3"
add_quarters(x, 2)
#> <year_quarter_day<January><quarter>[3]>
#> [1] "2019-Q3" "2019-Q4" "2020-Q1"
# Make the fiscal year start in March
y <- year_quarter_day(2019, 1:2, 1, start = 3)
y
#> <year_quarter_day<March><day>[2]>
#> [1] "2019-Q1-01" "2019-Q2-01"
add_quarters(y, 1)
#> <year_quarter_day<March><day>[2]>
#> [1] "2019-Q2-01" "2019-Q3-01"
# What year-month-day does this correspond to?
# Note that the fiscal year doesn't necessarily align with the Gregorian
# year!
as_year_month_day(add_quarters(y, 1))
#> <year_month_day<day>[2]>
#> [1] "2018-06-01" "2018-09-01"
```