[{'role': 'system', 'content': "You are an expert in machine learning and your task is to classify code snippets into one of the following categories: ['helper_functions', 'load_data', 'data_exploration', 'data_preprocessing', 'evaluation', 'modelling', 'prediction', 'result_visualization', 'save_results', 'comment_only']."}, {'role': 'user', 'content': "Identify the single most appropriate category to which the provided code belongs. Provide your response as a single category label without any additional information, commentary, or personal opinions.\\nPython Code:from sklearn.model_selection import GridSearchCV, ShuffleSplit\nfrom sklearn.metrics import make_scorer\n\nfrom sklearn.tree import DecisionTreeRegressor\n\nregressor = DecisionTreeRegressor(random_state=2)\n\ncv_sets = ShuffleSplit(n_splits=5, test_size=0.2)    \nparams = {'max_depth':range(10,40,2)}\nscoring_fnc = make_scorer(neg_rmspe)\n\ngrid = GridSearchCV(regressor,params,scoring_fnc,cv=cv_sets)\ngrid = grid.fit(train[features], np.log1p(train.Sales))\n\nDTR = grid.best_estimator_"}, {'role': 'assistant', 'content': 'modelling'}]