addAll method
Implementation
IntervalSet addAll(IntervalSet? set) {
if (set == null) {
return this;
}
final other = set;
// walk set and add each interval
final n = other.intervals.length;
for (var i = 0; i < n; i++) {
final I = other.intervals[i];
addRange(I.a, I.b);
}
return this;
}