[{'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:# define the base models\nbase_model = list()\nbase_model.append(('rf1', rf_model))\nbase_model.append(('rf2', rf_model_en))\nbase_model.append(('rf3', RandomForestRegressor(max_depth=8, max_features=0.1, min_samples_leaf=3, \n                                                min_samples_split=2, n_estimators=250, n_jobs=-1, oob_score=False)))\n# define meta learner model\nlearner = LinearRegression()\n# define the stacking ensemble\nstack2 = StackingRegressor(estimators=base_model, final_estimator=learner, cv=10)\n# fit the model on all available data\nstack2.fit(X, y)"}, {'role': 'assistant', 'content': 'modelling'}]