[{'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.linear_model import LinearRegression, Lasso, ElasticNet, Ridge\nfrom sklearn.tree import DecisionTreeRegressor\nfrom sklearn.neighbors import KNeighborsRegressor\nfrom sklearn.ensemble import GradientBoostingRegressor, RandomForestRegressor\nfrom sklearn.svm import SVR\nfrom sklearn.pipeline import Pipeline, make_pipeline\nfrom sklearn.preprocessing import StandardScaler, MaxAbsScaler, MinMaxScaler, Normalizer, minmax_scale, QuantileTransformer, RobustScaler, PolynomialFeatures\nfrom sklearn.model_selection import KFold, cross_val_score\n\nfrom xgboost import XGBRegressor'}, {'role': 'assistant', 'content': 'helper_functions'}]