def iso_year_and_week_one_start(wkst)
iso_year = self.year
date = ::Date.new(self.year, self.month, self.mday)
if (date >= ::Date.new(iso_year, 12, 29))
week_one_start = Calculations.iso_week_one(iso_year + 1, wkst)
if date < week_one_start
week_one_start = Calculations.iso_week_one(iso_year, wkst)
else
iso_year += 1
end
else
week_one_start = Calculations.iso_week_one(iso_year, wkst)
if (date < week_one_start)
iso_year -= 1
week_one_start = Calculations.iso_week_one(iso_year, wkst)
end
end
[iso_year, week_one_start]
end