golang 通过ISOWeek翻转得到周的日期时间

func firstDayOfISOWeek(year int, week int, timezone *time.Location) time.Time {
    date := time.Date(year, 0, 0, 0, 0, 0, 0, timezone)
    isoYear, isoWeek := date.ISOWeek()
    for date.Weekday() != time.Monday { // iterate back to Monday
        date = date.AddDate(0, 0, -1)
        isoYear, isoWeek = date.ISOWeek()
    }
    for isoYear < year { // iterate forward to the first day of the first week
        date = date.AddDate(0, 0, 1)
        isoYear, isoWeek = date.ISOWeek()
    }
    for isoWeek < week { // iterate forward to the first day of the given week
        date = date.AddDate(0, 0, 1)
        isoYear, isoWeek = date.ISOWeek()
    }
    return date
}