src/datetime.js
function possiblyCachedWeekData(dt) {
  if (dt.weekData === null) {
    dt.weekData = gregorianToWeek(dt.c);
  }
  return dt.weekData;
}
function possiblyCachedWeekData(dt) {
  if (dt.weekData === null) {
    dt.weekData = gregorianToWeek(dt.c);
  }
  return dt.weekData;
}
function possiblyCachedWeekData ( dt ) { if ( dt . weekData === null ) { dt . weekData = gregorianToWeek ( dt . c ) ; } return dt . weekData ; }
we cache week data on the DT object and this intermediates the cache
we cache week data on the DT object and this intermediates the cache