% ISO-8601 calendar weeks for \VAR{year}.
\BLOCK{for week, date in data.items()}
\BLOCK{set eow = date|eow(end_of_week)}
\newcommand{ISOWeek\VAR{week|num2words}}{\VAR{date.isoformat()}--\VAR{eow.isoformat()}}
\BLOCK{endfor}