namespace mlpack {
namespace structured_tree {

//please give it a better name, it is quite hard to come up a good name
class TreeOptions
{
  public:
    TreeOptions(); //default constructor

    void NumImages(size_t value) { numImages = value; }
    size_t NumImages() const { return numImages; }

   //other member functions

  private:
    size_t numImages;
    //other data members
};

}
}