add method
Implementation
int add(double l, double t, double r, double b, {required int category}) {
final id = _pool.add(l, t, r, b);
_cat[id] = category;
for (final (x, y) in _cellsFor(l, t, r, b)) {
final k = _h(x, y);
(_buckets[k] ??= <int>[]).add(id);
}
return id;
}