WeekNum_Year()

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#1

According to ISO-8601: January 1, 2000 is also 1999-W52-07. I can get the "W52" from "WeekNum", and the "07" from "WeekDay"; but currently, the only function that provides the year gives 2000, not 1999. Could we get an ISO-8601-compliant "WeekNum_Year" function that gives the year that's consistent with WeekNum?

Note that WeekNum_Year() would be equivalent to Year() except for up to the first or last three days of the Gregorian year.