This is a year-month-weekday method for the calendar_start()
and
calendar_end()
generics. They adjust components of a calendar to the
start or end of a specified precision
.
This method is restricted to only "year"
and "month"
precision
s, and
x
can't be more precise than month precision. Computing the "start" of
a day precision year-month-weekday object isn't defined because
a year-month-weekday with day = 1, index = 1
doesn't necessarily occur
earlier (chronologically) than day = 2, index = 1
. Because of these
restrictions, this method isn't particularly useful, but is included for
completeness.