text: public IntervalSet addAll(IntSet set) {if ( set==null ) {return this;}if (set instanceof IntervalSet) {IntervalSet other = (IntervalSet)set;int n = other.intervals.size();for (int i = 0; i < n; i++) {Interval I = other.intervals.get(i);this.add(I.a,I.b);}}else {for (int value : set.toList()) {add(value);}}return this;}