`as_weekday()`

converts to a weekday type. This is normally useful for
converting to a weekday from a sys-time or naive-time. You can use this
function along with the *circular arithmetic* that weekday implements to
easily get to the "next Monday" or "previous Sunday".

## Examples

```
x <- as_naive_time(year_month_day(2019, 01, 05))
# This is a Saturday!
as_weekday(x)
#> <weekday[1]>
#> [1] Sat
# See the examples in `?weekday` for more usage.
```