class Configure {
 public:
  size_t number_of_feature;      // number of features
  size_t max_depth;              // max depth for each tree
  size_t iterations;             // number of trees in gbdt
  double shrinkage;               // shrinkage parameter
  double feature_sample_ratio;    // portion of features to be splited
  double data_sample_ratio;       // portion of data to be fitted in each iteration
  size_t min_leaf_size;          // min number of nodes in leaf

  Loss loss;                     // loss type

  bool debug;                    // show debug info?

  double *feature_costs;         // mannually set feature costs in order to tune the model
  bool enable_feature_tunning;   // when set true, `feature_costs' is used to tune the model

  bool enable_initial_guess;
...
};