code: @Override
    public void fill(int from, int to)
    {
      ConciseSet toAdd = empty();
      toAdd.add(to);
      toAdd.complement();
      toAdd.add(to);
  
      ConciseSet toRemove = empty();
      toRemove.add(from);
      toRemove.complement();
  
      toAdd.removeAll(toRemove);
  
      this.addAll(toAdd);
    }
docs: {@inheritDoc}