This is a year-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_day
calendar_start(x, precision)
# S3 method for clock_year_day
calendar_end(x, precision)
Value
x at the same precision, but with some components altered to be
at the boundary value.