code: func (b *Bitmap) ForEachRange(start, end uint64, fn func(uint64)) {
  	itr := b.Iterator()
  	itr.Seek(start)
  	for v, eof := itr.Next(); !eof && v < end; v, eof = itr.Next() {
  		fn(v)
  	}
  }
docs: // ForEachRange executes fn for each value in the bitmap between [start, end).