This is a year-month-day method for the `calendar_start()`

and
`calendar_end()`

generics. They adjust components of a calendar to the
start or end of a specified `precision`

.

## Usage

```
# S3 method for clock_year_month_day
calendar_start(x, precision)
# S3 method for clock_year_month_day
calendar_end(x, precision)
```

## Arguments

- x
`[clock_year_month_day]`

A year-month-day vector.

- precision
`[character(1)]`

One of:

`"year"`

`"month"`

`"day"`

`"hour"`

`"minute"`

`"second"`

`"millisecond"`

`"microsecond"`

`"nanosecond"`

## Examples

```
# Hour precision
x <- year_month_day(2019, 2:4, 5, 6)
x
#> <year_month_day<hour>[3]>
#> [1] "2019-02-05T06" "2019-03-05T06" "2019-04-05T06"
# Compute the start of the month
calendar_start(x, "month")
#> <year_month_day<hour>[3]>
#> [1] "2019-02-01T00" "2019-03-01T00" "2019-04-01T00"
# Or the end of the month, notice that the hour value is adjusted as well
calendar_end(x, "month")
#> <year_month_day<hour>[3]>
#> [1] "2019-02-28T23" "2019-03-31T23" "2019-04-30T23"
# Compare that with just setting the day of the month to `"last"`, which
# doesn't adjust any other components
set_day(x, "last")
#> <year_month_day<hour>[3]>
#> [1] "2019-02-28T06" "2019-03-31T06" "2019-04-30T06"
# You can't compute the start / end at a more precise precision than
# the input is at
try(calendar_start(x, "second"))
#> Error in calendar_start_end_checks(x, x_precision, precision, "start") :
#> Can't compute the start of `x` (hour) at a more precise precision (second).
```