Function days_from_iso_week 

pub fn days_from_iso_week(iso_year: i64, week: u32, iso_weekday: u32) -> i64

The inverse of iso_week_from_days: the day number of an ISO-8601 week date (iso_year, week, iso_weekday) (week 1..=53, weekday 1..=7 Monday … Sunday).