problem_type     1718 apps/traincascade/old_ml.hpp     virtual bool problem_type() const;
problem_type      179 modules/ml/src/gbt.cpp     bool is_regression = problem_type();
problem_type     1028 modules/ml/src/gbt.cpp     data->is_classifier = !problem_type();
problem_type     1295 modules/ml/src/gbt.cpp     if ( !problem_type() )